glcpp: Add new test for #line directive.

This test exposes two current bugs:

	1. The source number is not being correctly emitted in error
	   messages (instead, it's always 0).

	2. A directive of "#line 0" is resulting in the following
	   parse error:

		preprocessor error: Invalid tokens after #

src/glsl/glcpp/tests/091-hash-line.c

@@ -0,0 +1,8 @@
+#line 0
+#error line 0 error
+#line 25
+#error line 25 error
+#line 0 1
+#error source 1, line 0 error
+#line 30 2
+#error source 2, line 30 error

src/glsl/glcpp/tests/091-hash-line.c.expected

@@ -0,0 +1,13 @@
+0:0(1): preprocessor error: #error line 0 error
+0:25(1): preprocessor error: #error line 25 error
+1:0(1): preprocessor error: #error source 1, line 0 error
+2:30(1): preprocessor error: #error source 2, line 30 error
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