checkpatch: improve OPEN_BRACE test

Some structure definitions that use macros trip the OPEN_BRACE test.

e.g. +struct bpf_map_def SEC("maps") control_map = {

Improve the test by using $balanced_parens instead of a .*

Miscellanea:

o Use $sline so any comments are ignored
o Correct the message output from declaration to definition
o Remove unnecessary parentheses

Link: http://lkml.kernel.org/r/db9b772999d1d2fbda3b9ee24bbca81a87837e13.1517543491.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Reported-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -3919,10 +3919,12 @@ sub process {
 
 # function brace can't be on same line, except for #defines of do while,
 # or if closed on same line
-		if (($line=~/$Type\s*$Ident\(.*\).*\s*{/) and
-		    !($line=~/\#\s*define.*do\s\{/) and !($line=~/}/)) {
+		if ($^V && $^V ge 5.10.0 &&
+		    $sline =~ /$Type\s*$Ident\s*$balanced_parens\s*\{/ &&
+		    $sline !~ /\#\s*define\b.*do\s*\{/ &&
+		    $sline !~ /}/) {
 			if (ERROR("OPEN_BRACE",
-				  "open brace '{' following function declarations go on the next line\n" . $herecurr) &&
+				  "open brace '{' following function definitions go on the next line\n" . $herecurr) &&
 			    $fix) {
 				fix_delete_line($fixlinenr, $rawline);
 				my $fixed_line = $rawline;