check-package: Flag usage of '\t \\$'.

check-package would flag tabs before a backslash ('\t\\'),
two spaces before a backslash ('  \\') but would not flag a tab before space
before backslash ('\t \\'), allowing someone to bypass the check.

Signed-off-by: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
Reviewed-by: Ricardo Martincoski <ricardo.martincoski@datacom.ind.br>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

utils/checkpackagelib/lib_mk.py

@@ -123,7 +123,7 @@ class RemoveDefaultPackageSourceVariable(_CheckFunction):
 
 
 class SpaceBeforeBackslash(_CheckFunction):
-    TAB_OR_MULTIPLE_SPACES_BEFORE_BACKSLASH = re.compile(r"^.*(  |\t)\\$")
+    TAB_OR_MULTIPLE_SPACES_BEFORE_BACKSLASH = re.compile(r"^.*(  |\t ?)\\$")
 
     def check_line(self, lineno, text):
         if self.TAB_OR_MULTIPLE_SPACES_BEFORE_BACKSLASH.match(text.rstrip()):