Merge pull request AFLplusplus#38 from floyd-fuh/master

Unset AFL_CC

Makefile

@@ -157,7 +157,7 @@ ifndef AFL_NO_X86
 
 test_build: afl-gcc afl-as afl-showmap
 	@echo "[*] Testing the CC wrapper and instrumentation output..."
-	unset AFL_USE_ASAN AFL_USE_MSAN; AFL_QUIET=1 AFL_INST_RATIO=100 AFL_PATH=. ./$(TEST_CC) $(CFLAGS) test-instr.c -o test-instr $(LDFLAGS)
+	unset AFL_USE_ASAN AFL_USE_MSAN AFL_CC; AFL_QUIET=1 AFL_INST_RATIO=100 AFL_PATH=. ./$(TEST_CC) $(CFLAGS) test-instr.c -o test-instr $(LDFLAGS)
 	echo 0 | ./afl-showmap -m none -q -o .test-instr0 ./test-instr
 	echo 1 | ./afl-showmap -m none -q -o .test-instr1 ./test-instr
 	@rm -f test-instr