This breaks code that declares `errno` itself for whatever crazy reason:
b.c:22:12: error: conflicting types for '__errno'
extern int errno;
^
/usr/local/google/ndkports/toolchain/bin/../sysroot/usr/include/errno.h:47:20: note: expanded from macro 'errno'
#define errno (*__errno())
^
/usr/local/google/ndkports/toolchain/bin/../sysroot/usr/include/errno.h:44:15: note: previous declaration is here
volatile int* __errno(void) __attribute_const__;
^
Bug: N/A
Test: built various bits of GNU source
Change-Id: I27c03bf3bde419a001f98f1ea6c267c847f31271
