Cleaning UEFI Build with additional OPENSSL_SYS_UEFI flags

Add OPENSSL_SYS_UEFI to remove unused syslog and uid stuffs for
more clean UEFI build.
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2961)

crypto/uid.c

@@ -19,7 +19,7 @@ int OPENSSL_issetugid(void)
     return issetugid();
 }
 
-#elif defined(OPENSSL_SYS_WIN32) || defined(OPENSSL_SYS_VXWORKS)
+#elif defined(OPENSSL_SYS_WIN32) || defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)
 
 int OPENSSL_issetugid(void)
 {

e_os.h

@@ -87,7 +87,7 @@ extern "C" {
 #  define DEVRANDOM_EGD "/var/run/egd-pool","/dev/egd-pool","/etc/egd-pool","/etc/entropy"
 # endif
 
-# if defined(OPENSSL_SYS_VXWORKS)
+# if defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)
 #  define NO_SYS_PARAM_H
 #  define NO_CHMOD
 #  define NO_SYSLOG