Detect blank lines before trying to parse variables.

This makes the parser slightly faster in common files.

Author: dmsc

src/basic.syn

@@ -652,7 +652,7 @@ SKIP_COMMENT:
 
 PARSE_START: statement or variable assignment
         PARSE_LINE_COMMAND SKIP_COMMENT
-        PARSE_LINE_ASSIGN SKIP_COMMENT
         SKIP_COMMENT
+        PARSE_LINE_ASSIGN SKIP_COMMENT
 
 # vi:syntax=perl