utils: Provide a fallback for sigwaitinfo() if needed

Apparently, not available on Mac OS X 10.10 Yosemite. We don't provide
this on Windows.

src/libstrongswan/utils/compat/android.h

@@ -21,8 +21,6 @@
 #ifndef ANDROID_H_
 #define ANDROID_H_
 
-#include <android/api-level.h>
-
 /* stuff defined in AndroidConfig.h, which is included using the -include
  * command-line option, thus cannot be undefined using -U CFLAGS options.
  * the reason we have to undefine these flags in the first place, is that
@@ -30,30 +28,4 @@
  * actually defined. */
 #undef HAVE_BACKTRACE
 
-/* sigwaitinfo() is not defined up to this API level, provide a fallback */
-#if __ANDROID_API__ <= 21
-#include <errno.h>
-#include <signal.h>
-
-static inline int sigwaitinfo(const sigset_t *set, void *info)
-{
-	int sig, err;
-
-	if (info)
-	{	/* we don't replicate siginfo_t, which we don't use */
-		errno = EINVAL;
-		return -1;
-	}
-	err = sigwait(set, &sig);
-	if (err != 0)
-	{
-		errno = err;
-		sig = -1;
-	}
-	return sig;
-}
-#else
-#error Check availability of sigwaitinfo() in this API level
-#endif
-
 #endif /** ANDROID_H_ @}*/