checksrc: escape open brace in regex

#                            | (__| |_| |  _ <| |___

#                             \___|\___/|_| \_\_____|

#

# Copyright (C) 2011 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.

# Copyright (C) 2011 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.

#

# This software is licensed as described in the file COPYING, which

# you should have received as part of this distribution. The terms

        # check for 'void func() {', but avoid false positives by requiring

        # both an open and closed parentheses before the open brace

        if($l =~ /^((\w).*){\z/) {

        if($l =~ /^((\w).*)\{\z/) {

            my $k = $1;

            $k =~ s/const *//;

            $k =~ s/static *//;