Checks getrandom availability on solaris.

To fix part of GH-15381.
gcc nor clang provides a constant to distinguish illumos and solaris
not the system provides a kernel version stamp like the BSD.
thus, we simply check the symbol and remaing purposely conservative in
the existing logic, using it only for solaris to avoid unexpected
breakages for other systems. would need a different fix for higher
branches.

Close GH-15390

Author: devnexen

ext/random/config.m4

@@ -14,6 +14,11 @@ AC_CHECK_HEADERS([CommonCrypto/CommonRandom.h], [], [],
 	#include <CommonCrypto/CommonCryptoError.h>
 ])
 
+dnl
+dnl Mostly for non Linux systems
+dnl
+AC_CHECK_FUNCS([getrandom])
+
 dnl
 dnl Setup extension
 dnl

ext/random/csprng.c

@@ -46,7 +46,7 @@
 #if HAVE_SYS_PARAM_H
 # include <sys/param.h>
 # if (__FreeBSD__ && __FreeBSD_version > 1200000) || (__DragonFly__ && __DragonFly_version >= 500700) || \
-     defined(__sun) || (defined(__NetBSD__) && __NetBSD_Version__ >= 1000000000)
+     (defined(__sun) && defined(HAVE_GETRANDOM)) || (defined(__NetBSD__) && __NetBSD_Version__ >= 1000000000)
 #  include <sys/random.h>
 # endif
 #endif
@@ -98,7 +98,7 @@ PHPAPI zend_result php_random_bytes(void *bytes, size_t size, bool should_throw)
 #else
 	size_t read_bytes = 0;
 # if (defined(__linux__) && defined(SYS_getrandom)) || (defined(__FreeBSD__) && __FreeBSD_version >= 1200000) || (defined(__DragonFly__) && __DragonFly_version >= 500700) || \
-  defined(__sun) || (defined(__NetBSD__) && __NetBSD_Version__ >= 1000000000)
+  (defined(__sun) && defined(HAVE_GETRANDOM)) || (defined(__NetBSD__) && __NetBSD_Version__ >= 1000000000)
 	/* Linux getrandom(2) syscall or FreeBSD/DragonFlyBSD/NetBSD getrandom(2) function
 	 * Being a syscall, implemented in the kernel, getrandom offers higher quality output
 	 * compared to the arc4random api albeit a fallback to /dev/urandom is considered.