pcre2: Update to upstream version 10.42 (take two)

Changelog: https://github.com/PCRE2Project/pcre2/blob/pcre2-10.42/ChangeLog

This fixes support for RISC-V architectures in the sljit library, so we
enable the module's compilation for `rv64` too.

(cherry picked from commit e289cf7085)

modules/regex/config.py

@@ -1,5 +1,5 @@
 def can_build(env, platform):
-    return not env["arch"].startswith("rv")
+    return True
 
 
 def configure(env):

modules/regex/regex.cpp

@@ -40,7 +40,9 @@ static void *_regex_malloc(PCRE2_SIZE size, void *user) {
 }
 
 static void _regex_free(void *ptr, void *user) {
-	memfree(ptr);
+	if (ptr) {
+		memfree(ptr);
+	}
 }
 
 int RegExMatch::_find(const Variant &p_name) const {