merge from psm: hide more brk

libc/sysdeps/linux/common/sbrk.c

@@ -7,16 +7,15 @@
 #include <unistd.h>
 #include <errno.h>
 
-libc_hidden_proto(sbrk)
-
 libc_hidden_proto(brk)
 
 /* Defined in brk.c.  */
-extern void *__curbrk;
+extern void *__curbrk attribute_hidden;
 
 /* Extend the process's data space by INCREMENT.
    If INCREMENT is negative, shrink data space by - INCREMENT.
    Return start of new space allocated, or -1 for errors.  */
+libc_hidden_proto(sbrk)
 void * sbrk (intptr_t increment)
 {
     void *oldbrk;