lbutils: only use GNU SOURCE for syscall

and remove manual prototypes; fchmod, realpath
and so on rely on the _XOPEN_SOURCE macro.

the POSIX macro wasn't needed: _XOPEN_SOURCE
is sufficient.

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/libreboot-utils/include/common.h

@@ -13,18 +13,6 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <limits.h>
-#include <errno.h>
-
-/* for linux getrandom
- */
-#if defined(__linux__)
-#include <sys/random.h>
-#include <sys/syscall.h>
-#endif
-
-#ifdef __OpenBSD__ /* for pledge */
-#include <unistd.h>
-#endif
 
 /* dangerously cool macros:
  */
@@ -49,10 +37,6 @@
 /* system prototypes
  */
 
-int fchmod(int fd, mode_t mode);
-char *realpath(const char *path,
-    char *resolved);
-
 #ifndef USE_URANDOM
 #define USE_URANDOM 0
 #endif