Fix line number handling in line directive callback.

The line argument passed into the lineCallback function is the
literal value of the first argument of the #line directive.
lastLine in DoPreprocessing() should be updated taking into
consideration the different definitions for #line between specs.

Add a test to reveal the bug.

Test/test-preprocessor-list

@@ -3,5 +3,6 @@ preprocessor.errors.vert
 preprocessor.extensions.vert
 preprocessor.function_macro.vert
 preprocessor.line.vert
+preprocessor.line.frag
 preprocessor.pragma.vert
 preprocessor.simple.vert