mpers.awk: avoid redefinition of mpers_ptr_t

Older versions of gcc like those found in RHEL6 fail with the following
diagnostics:

  In file included from block.c:32:
  ./mpers-m32/struct_blk_user_trace_setup.h:2: error: redefinition of typedef ‘mpers_ptr_t’
  mpers_type.h:44: note: previous declaration of ‘mpers_ptr_t’ was here

* mpers.awk (END): Add #ifndef guard to mpers_ptr_t typedef.
* mpers_test.sh: Update expected output.

mpers.awk

@@ -234,8 +234,12 @@ END {
 	PROCINFO["sorted_in"] = "compare_indices"
 	for (item in array) {
 		if (array[item]["special"] == "pointer_type") {
-			print "typedef uint" \
+			mpers_ptr_t = \
-				8 * array_get(item, "byte_size") "_t mpers_ptr_t;"
+				"uint" 8 * array_get(item, "byte_size") "_t"
+			print "#ifndef mpers_ptr_t_is_" mpers_ptr_t
+			print "typedef " mpers_ptr_t " mpers_ptr_t;"
+			print "#define mpers_ptr_t_is_" mpers_ptr_t
+			print "#endif"
 			break
 		}
 	}

mpers_test.sh

@@ -81,9 +81,13 @@ typedef struct {
 EOF
 
 expected="$mpers_dir/sample.expected"
+mpers_ptr_t="uint${size}_t"
 cat > "$expected" <<EOF
 #include <inttypes.h>
-typedef uint${size}_t mpers_ptr_t;
+#ifndef mpers_ptr_t_is_${mpers_ptr_t}
+typedef ${mpers_ptr_t} mpers_ptr_t;
+#define mpers_ptr_t_is_${mpers_ptr_t}
+#endif
 typedef
 struct {
 struct {