checkpatch: don't complain about LEADING_SPACE in CPP continuations

If a C preprocessor macro is continued onto another line using
a backslash line continuation, checkpatch.pl will complain about leading
spaces used to indent the multiline conditional.

This leads to warnings similar to the following

  WARNING: please, no spaces at the start of a line
  torvalds#107: FILE: arch/m68k/include/asm/mcfgpio.h:107:
  +    defined(CONFIG_M53xx) || defined(CONFIG_M54xx) || \$

  WARNING: please, no spaces at the start of a line
  torvalds#108: FILE: arch/m68k/include/asm/mcfgpio.h:108:
  +    defined(CONFIG_M5441x)$

To fix these warnings, modify the test to also exclude lines which end
in a backslach continuation, as these lines should only occur within
a multiline C Preprocessor check.

Signed-off-by: Jacob Keller <[email protected]>

Author: jacob-keller

scripts/checkpatch.pl

@@ -3355,7 +3355,8 @@ sub process {
 #  1) within comments
 #  2) indented preprocessor commands
 #  3) hanging labels
-		if ($rawline =~ /^\+ / && $line !~ /^\+ *(?:$;|#|$Ident:)/)  {
+		if ($rawline =~ /^\+ / && $line !~ /^\+ *(?:$;|#|$Ident:)/ &&
+		    $prevline !~ /\\$/)  {
 			my $herevet = "$here\n" . cat_vet($rawline) . "\n";
 			if (WARN("LEADING_SPACE",
 				 "please, no spaces at the start of a line\n" . $herevet) &&