glcpp: Add several tests for diagnostics.
Which are proving to be useful since some of these tests are not yet
acting as desired, (in particular, the unterminated if test is not
generating any diagnostic).
diff --git a/src/glsl/glcpp/tests/080-if-without-expression.c.expected b/src/glsl/glcpp/tests/080-if-without-expression.c.expected
new file mode 100644
index 0000000..1a3e383
--- /dev/null
+++ b/src/glsl/glcpp/tests/080-if-without-expression.c.expected
@@ -0,0 +1,3 @@
+0:2(1): preprocessor error: #if with no expression
+
+