deal with //-style comments in foreign assembly code.
(for example, go.) the reason // comments previously
would not work is that // does not emit a ';' symbol for
the \n as a uncommented \n would.

Reference: /n/sources/patch/applied/asmcmt
Date: Sat Nov 21 21:41:17 CET 2009
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/cc/lexbody	Sat Nov 21 21:37:54 2009
+++ /sys/src/cmd/cc/lexbody	Sat Nov 21 21:37:51 2009
@@ -417,10 +417,8 @@
 		if(c1 == '/') {
 			for(;;) {
 				c = GETC();
-				if(c == '\n') {
-					lineno++;
-					goto l0;
-				}
+				if(c == '\n')
+					goto l1;
 				if(c == EOF) {
 					yyerror("eof in comment");
 					errorexit();