checkpatch: improve "no space after cast" test

Some false positives exist on this test.

For instance:
	*va_arg(args, signed char *) = val.s;
or
	memset(foo, 0, sizeof(struct bar *) * baz));

Ignore lines that have an arithmetic operator or assignment
after what appears to be a cast to a pointer "(foo *)".

Add $Arithmetic convenience variable.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -241,10 +241,11 @@ our $Float	= qr{$Float_hex|$Float_dec|$Float_int};
 our $Constant	= qr{$Float|$Binary|$Hex|$Int};
 our $Assignment	= qr{\*\=|/=|%=|\+=|-=|<<=|>>=|&=|\^=|\|=|=};
 our $Compare    = qr{<=|>=|==|!=|<|>};
+our $Arithmetic = qr{\+|-|\*|\/|%};
 our $Operators	= qr{
 			<=|>=|==|!=|
 			=>|->|<<|>>|<|>|!|~|
-			&&|\|\||,|\^|\+\+|--|&|\||\+|-|\*|\/|%
+			&&|\|\||,|\^|\+\+|--|&|\||$Arithmetic
 		  }x;
 
 our $NonptrType;
@@ -1885,7 +1886,7 @@ sub process {
 			}
 		}
 
-		if ($line =~ /^\+.*\*[ \t]*\)[ \t]+/) {
+		if ($line =~ /^\+.*\*[ \t]*\)[ \t]+(?!$Assignment|$Arithmetic)/) {
 			CHK("SPACING",
 			    "No space is necessary after a cast\n" . $hereprev);
 		}