Fix locale switch back to C in pcre

The compile context is shared between patterns, so we need to set
the character tables unconditionally in case we switched from
a non-C locale to the C locale.

Author: nikic

ext/pcre/php_pcre.c

@@ -767,8 +767,8 @@ PHPAPI pcre_cache_entry* pcre_get_compiled_regex_cache_ex(zend_string *regex, in
 			zend_hash_add_ptr(&char_tables, _k, (void *)tables);
 			zend_string_release(_k);
 		}
-		pcre2_set_character_tables(cctx, tables);
 	}
+	pcre2_set_character_tables(cctx, tables);
 
 	/* Set extra options for the compile context. */
 	if (PHP_PCRE_DEFAULT_EXTRA_COPTIONS != extra_coptions) {

ext/pcre/tests/ctype_back_to_c.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Changing LC_CTYPE back to C
+--SKIPIF--
+<?php
+if (!setlocale(LC_CTYPE, "de_DE", "de-DE")) die("skip requires de_DE locale");
+?>
+--FILE--
+<?php
+var_dump(setlocale(LC_CTYPE, "de_DE", "de-DE") !== false);
+var_dump(preg_match('/\w/', "\xe4"));
+var_dump(setlocale(LC_CTYPE, "C") !== false);
+var_dump(preg_match('/\w/', "\xe4"));
+?>
+--EXPECT--
+bool(true)
+int(1)
+bool(true)
+int(0)