don't make __errno_location / __h_errno_location hidden

Closes #2089 (https://bugs.busybox.net/show_bug.cgi?id=2089)

__errno_location / __h_errno_location access has to go through the PLT
like malloc/free, so the linuxthread variants gets used instead when
compiling with -pthread.

Based on http://github.com/mat-c/uClibc/commit/328d392c54aa5dc2b8e7f398a419087de497de2b

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Austin Foxley <austinf@cetoncorp.com>

include/netdb.h

@@ -59,7 +59,6 @@ __BEGIN_DECLS
 
 /* Function to get address of global `h_errno' variable.  */
 extern int *__h_errno_location (void) __THROW __attribute__ ((__const__));
-libc_hidden_proto(__h_errno_location)
 
 /* Macros for accessing h_errno from inside libc.  */
 #ifdef _LIBC

libc/misc/internals/__errno_location.c

@@ -15,6 +15,3 @@ __errno_location (void)
 {
     return &errno;
 }
-#ifdef IS_IN_libc /* not really need, only to keep in sync w/ libc_hidden_proto */
-libc_hidden_weak(__errno_location)
-#endif

libc/misc/internals/__h_errno_location.c

@@ -10,4 +10,3 @@ int * weak_const_function __h_errno_location (void)
 {
     return &h_errno;
 }
-libc_hidden_weak(__h_errno_location)

libc/sysdeps/linux/common/bits/errno.h

@@ -43,7 +43,6 @@
 # ifndef __ASSEMBLER__
 /* Function to get address of global `errno' variable.  */
 extern int *__errno_location (void) __THROW __attribute__ ((__const__));
-libc_hidden_proto(__errno_location)
 
 #  ifdef __UCLIBC_HAS_THREADS__
 /* When using threads, errno is a per-thread value.  */

libc/sysdeps/linux/common/bits/uClibc_errno.h

@@ -33,9 +33,6 @@ extern int *__errno_location (void) __THROW __attribute__ ((__const__))
 ;
 # if defined __UCLIBC_HAS_THREADS__
 #  include <tls.h>
-#  if defined USE___THREAD && USE___THREAD
-libc_hidden_proto(__errno_location)
-#  endif
 # endif
 
 #endif /* !__ASSEMBLER__ */