test(format): pin the macro-layout crashers as corpus seeds

The two inputs the expansion round-trip target was built for, the object
macro with a parenthesised body and the continuation-only macro body,
enter the seed corpus so every plain go test run replays them.

Assisted-by: GLM 5.3

format/testdata/fuzz/FuzzFormatExpansionRoundTrip/2e57951e124dc12b

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("#define M() \\\n\tADD $1, R0 \\\n\tSUB $2, R1\nM()\n")

format/testdata/fuzz/FuzzFormatExpansionRoundTrip/fab61ade833f43b6

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("#define M (BX)\nMOVL M, AX\n")