Hide the __bionic_clone and __bionic_clone_entry implementation details.

clone(2) is the public symbol.

Also switch a test from __bionic_clone to clone; testing public API
means the test now works on glibc too.

Change-Id: If59def26a00c3afadb8a6cf9442094c35a59ffde
diff --git a/libc/arch-arm/bionic/__bionic_clone.S b/libc/arch-arm/bionic/__bionic_clone.S
index 7b76f5e..7cc4db5 100644
--- a/libc/arch-arm/bionic/__bionic_clone.S
+++ b/libc/arch-arm/bionic/__bionic_clone.S
@@ -71,3 +71,4 @@
     ldr    r1, [sp, #-8]
     b      __bionic_clone_entry
 END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/arch-arm64/bionic/__bionic_clone.S b/libc/arch-arm64/bionic/__bionic_clone.S
index 9790291..af91320 100644
--- a/libc/arch-arm64/bionic/__bionic_clone.S
+++ b/libc/arch-arm64/bionic/__bionic_clone.S
@@ -61,3 +61,4 @@
     ldp     x0, x1, [sp, #-16]
     b       __bionic_clone_entry
 END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/arch-mips/bionic/__bionic_clone.S b/libc/arch-mips/bionic/__bionic_clone.S
index 9273134..11d596b 100644
--- a/libc/arch-mips/bionic/__bionic_clone.S
+++ b/libc/arch-mips/bionic/__bionic_clone.S
@@ -66,3 +66,4 @@
 	la	t9,__set_errno
 	j	t9
 END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/arch-mips64/bionic/__bionic_clone.S b/libc/arch-mips64/bionic/__bionic_clone.S
index e1ade30..754861b 100644
--- a/libc/arch-mips64/bionic/__bionic_clone.S
+++ b/libc/arch-mips64/bionic/__bionic_clone.S
@@ -95,3 +95,4 @@
 	PTR_ADDU sp,FRAMESZ
 	j	t9
 	END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/arch-x86/bionic/__bionic_clone.S b/libc/arch-x86/bionic/__bionic_clone.S
index e6ddaaa..bc7f71d 100644
--- a/libc/arch-x86/bionic/__bionic_clone.S
+++ b/libc/arch-x86/bionic/__bionic_clone.S
@@ -51,3 +51,4 @@
         popl    %ebx
         ret
 END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/arch-x86_64/bionic/__bionic_clone.S b/libc/arch-x86_64/bionic/__bionic_clone.S
index cf98d76..c2ebebd 100644
--- a/libc/arch-x86_64/bionic/__bionic_clone.S
+++ b/libc/arch-x86_64/bionic/__bionic_clone.S
@@ -70,3 +70,4 @@
 2:
         ret
 END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/bionic/clone.cpp b/libc/bionic/clone.cpp
index 1d997fe..4ea3c70 100644
--- a/libc/bionic/clone.cpp
+++ b/libc/bionic/clone.cpp
@@ -35,7 +35,7 @@
 extern "C" void __exit(int status);
 
 // Called from the __bionic_clone assembler to call the thread function then exit.
-extern "C" void __bionic_clone_entry(int (*fn)(void*), void* arg) {
+extern "C" __LIBC_HIDDEN__ void __bionic_clone_entry(int (*fn)(void*), void* arg) {
   int status = (*fn)(arg);
   __exit(status);
 }