Clean up gcc line

tests/Makefile

@@ -14,17 +14,18 @@ clean:
 run: $(BINS)
 	for bin in $(BINS); do echo "\\033[1m$${bin}\\033[0m"; ./$${bin} test args; done
 
+GCCHEAD=\
+	-nostdinc \
+	-nostdlib \
+	-I ../include \
+	-I ../target/include \
+	-I ../openlibm/include \
+	-I ../openlibm/src \
+	../target/debug/libcrt0.a
+
+GCCTAIL=\
+	../target/debug/libc.a \
+	../openlibm/libopenlibm.a
+
 %: %.c
-	gcc \
-		-fno-stack-protector \
-		-nostdinc \
-		-nostdlib \
-		-I ../include \
-		-I ../target/include \
-		-I ../openlibm/include \
-		-I ../openlibm/src \
-		../target/debug/libcrt0.a \
-		$< \
-		../target/debug/libc.a \
-		../openlibm/libopenlibm.a \
-		-o $@
+	gcc -fno-stack-protector $(GCCHEAD) $< $(GCCTAIL) -o $@