libc: Add ftruncate64 and improve 64-bit parameter syscall handling.

This patch improves the handling of 64-bit parameters in syscalls on ARM.
The ARM EABI mandates that 64-bit quantities be passed in even/odd register
pairs, which requires special treatment.

This allows us to simplify our implementations of pread() and pwrite()
and remove the C stubs for pread64() and pwrite64().

Also add ftruncate64() to <unistd.h>

Change-Id: I407e2fd223ba0093dd2d0b04c6152fadfc9ce3ef

Bug 3107933
diff --git a/libc/unistd/pread.c b/libc/unistd/pread.c
index ec4691a..42fc3bc 100644
--- a/libc/unistd/pread.c
+++ b/libc/unistd/pread.c
@@ -28,10 +28,8 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-extern int __pread64(int fd, void *buf, size_t nbytes, loff_t offset);
-
 ssize_t pread(int fd, void *buf, size_t nbytes, off_t offset)
 {
-    return __pread64(fd, buf, nbytes, offset);
+    return pread64(fd, buf, nbytes, (off64_t)offset);
 }
 
diff --git a/libc/unistd/pread64.c b/libc/unistd/pread64.c
deleted file mode 100644
index 2a4e08c..0000000
--- a/libc/unistd/pread64.c
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * Copyright (C) 2010 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *  * Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- *  * Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-#include <sys/types.h>
-#include <unistd.h>
-
-extern int __pread64(int fd, void *buf, size_t nbytes, loff_t offset);
-
-ssize_t pread64(int fd, void *buf, size_t nbytes, off64_t offset)
-{
-    return __pread64(fd, buf, nbytes, offset);
-}
-
diff --git a/libc/unistd/pwrite.c b/libc/unistd/pwrite.c
index 223e1b3..f106cb3 100644
--- a/libc/unistd/pwrite.c
+++ b/libc/unistd/pwrite.c
@@ -28,10 +28,8 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-extern int __pwrite64(int fd, const void *buf, size_t nbytes, loff_t offset);
-
 ssize_t pwrite(int fd, const void *buf, size_t nbytes, off_t offset)
 {
-    return __pwrite64(fd, buf, nbytes, offset);
+    return pwrite64(fd, buf, nbytes, (off64_t)offset);
 }
 
diff --git a/libc/unistd/pwrite64.c b/libc/unistd/pwrite64.c
deleted file mode 100644
index b084650..0000000
--- a/libc/unistd/pwrite64.c
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * Copyright (C) 2010 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *  * Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- *  * Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-#include <sys/types.h>
-#include <unistd.h>
-
-extern int __pwrite64(int fd, const void *buf, size_t nbytes, loff_t offset);
-
-ssize_t pwrite64(int fd, const void *buf, size_t nbytes, off64_t offset)
-{
-    return __pwrite64(fd, buf, nbytes, offset);
-}
-