tests: Fix double expansion bugs in test code

Two test programs - check_path and overlay - define a CHECK() helper macro
in such a way that in the case of an error it will re-execute the checked
code fragment, instead of using the return value from the initial call.

This can lead to misreporting errors, because the code may fail in a
different way the second time around due to changes made during the first
failing call.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

tests/check_path.c

@@ -26,8 +26,9 @@
 
 #define CHECK(code) \
 	{ \
-		if (code) \
-			FAIL(#code ": %s", fdt_strerror(code)); \
+		int err = (code); \
+		if (err) \
+			FAIL(#code ": %s", fdt_strerror(err)); \
 	}
 
 /* 4k ought to be enough for anybody */

tests/overlay.c

@@ -27,8 +27,9 @@
 
 #define CHECK(code) \
 	{ \
-		if (code) \
-			FAIL(#code ": %s", fdt_strerror(code)); \
+		int err = (code); \
+		if (err) \
+			FAIL(#code ": %s", fdt_strerror(err)); \
 	}
 
 /* 4k ought to be enough for anybody */