Move gdb_regex to gdbsupport

This moves the gdb_regex convenience class to gdbsupport.

gdbsupport/gdb_regex.cc

@@ -0,0 +1,57 @@
+/* Copyright (C) 2011-2022 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include "gdb_regex.h"
+#include "gdbsupport/def-vector.h"
+
+compiled_regex::compiled_regex (const char *regex, int cflags,
+				const char *message)
+{
+  gdb_assert (regex != NULL);
+  gdb_assert (message != NULL);
+
+  int code = regcomp (&m_pattern, regex, cflags);
+  if (code != 0)
+    {
+      size_t length = regerror (code, &m_pattern, NULL, 0);
+      gdb::def_vector<char> err (length);
+
+      regerror (code, &m_pattern, err.data (), length);
+      error (("%s: %s"), message, err.data ());
+    }
+}
+
+compiled_regex::~compiled_regex ()
+{
+  regfree (&m_pattern);
+}
+
+int
+compiled_regex::exec (const char *string, size_t nmatch,
+		      regmatch_t pmatch[], int eflags) const
+{
+  return regexec (&m_pattern, string, nmatch, pmatch, eflags);
+}
+
+int
+compiled_regex::search (const char *string,
+			int length, int start, int range,
+			struct re_registers *regs)
+{
+  return re_search (&m_pattern, string, length, start, range, regs);
+}