Implement some of the missing LFS64 support.

This gives us:

* <dirent.h>
  struct dirent64
  readdir64, readdir64_r, alphasort64, scandir64

* <fcntl.h>
  creat64, openat64, open64.

* <sys/stat.h>
  struct stat64
  fstat64, fstatat64, lstat64, stat64.

* <sys/statvfs.h>
  struct statvfs64
  statvfs64, fstatvfs64.

* <sys/vfs.h>
  struct statfs64
  statfs64, fstatfs64.

This also removes some of the incorrect #define hacks we've had in the
past (for stat64, for example, which we promised to clean up way back
in bug 8472078).

Bug: 11865851
Bug: 8472078
Change-Id: Ia46443521918519f2dfa64d4621027dfd13ac566
diff --git a/libc/bionic/stat.cpp b/libc/bionic/stat.cpp
index 62387c5..e71d9d4 100644
--- a/libc/bionic/stat.cpp
+++ b/libc/bionic/stat.cpp
@@ -34,3 +34,4 @@
 int stat(const char* path, struct stat* sb) {
   return fstatat(AT_FDCWD, path, sb, 0);
 }
+__strong_alias(stat64, stat);