glcpp: Add two new tests for testing redefined macros.

The specification says that redefining a macro is an error, unless the
new definitions is identical to the old one, (identical replacement
lists but ignoring differing amounts of whitespace).

src/glsl/glcpp/tests/088-redefine-macro-legitimate.c

@@ -0,0 +1,5 @@
+#define abc 123
+#define abc 123
+
+#define foo(x) (x)+23
+#define foo(x) ( x ) + 23

src/glsl/glcpp/tests/088-redefine-macro-legitimate.c.expected

@@ -0,0 +1,6 @@
+
+
+
+
+
+

src/glsl/glcpp/tests/089-redefine-macro-error.c

@@ -0,0 +1,17 @@
+#define x y
+#define x z
+
+#define abc 123
+#define abc() 123
+
+#define foo() bar
+#define foo(x) bar
+
+#define bar() baz
+#define bar baz
+
+#define biff(a,b) a+b
+#define biff(a,b,c) a+b
+
+#define oper(a,b) a+b
+#define oper(a,b) a*b

src/glsl/glcpp/tests/089-redefine-macro-error.c.expected

@@ -0,0 +1,30 @@
+0:2(9): preprocessor error: Redefinition of macro x
+
+0:5(9): preprocessor error: Redefinition of macro abc
+
+0:8(9): preprocessor error: Redefinition of macro foo
+
+0:11(9): preprocessor error: Redefinition of macro bar
+
+0:14(9): preprocessor error: Redefinition of macro biff
+
+0:17(9): preprocessor error: Redefinition of macro oper
+
+
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