Fix undefined behavior (left shift of negative number)

Fixes oss-fuzz #68722

Author: dstogov

ext/standard/image.c

@@ -749,10 +749,10 @@ static signed short php_ifd_get16s(void *Short, int motorola_intel)
 static int php_ifd_get32s(void *Long, int motorola_intel)
 {
 	if (motorola_intel) {
-		return  ((( char *)Long)[0] << 24) | (((unsigned char *)Long)[1] << 16)
-		      | (((unsigned char *)Long)[2] << 8 ) | (((unsigned char *)Long)[3] << 0 );
+		return  ((unsigned)((( char *)Long)[0]) << 24) | (((unsigned char *)Long)[1] << 16)
+		      | ((( char *)Long)[2] << 8 ) | (((unsigned char *)Long)[3] << 0 );
 	} else {
-		return  ((( char *)Long)[3] << 24) | (((unsigned char *)Long)[2] << 16)
+		return  ((unsigned)((( char *)Long)[3]) << 24) | (((unsigned char *)Long)[2] << 16)
 		      | (((unsigned char *)Long)[1] << 8 ) | (((unsigned char *)Long)[0] << 0 );
 	}
 }