S390: Disable gcc generation of mul-add in cctests

test/cctest/cctest.gyp

Index: test/cctest/cctest.gyp
diff --git a/test/cctest/cctest.gyp b/test/cctest/cctest.gyp
index 4d9ef0e286a60276527612e489c14270d58dd839..529aab3a03635d381a829d254f92281f04643101 100644
--- a/test/cctest/cctest.gyp
+++ b/test/cctest/cctest.gyp
@@ -314,7 +314,8 @@
           },
         }],
         ['v8_target_arch=="ppc" or v8_target_arch=="ppc64" \
-          or v8_target_arch=="arm" or v8_target_arch=="arm64"', {
+          or v8_target_arch=="arm" or v8_target_arch=="arm64" \
+          or v8_target_arch=="s390" or v8_target_arch=="s390x"', {
           # disable fmadd/fmsub so that expected results match generated code in
           # RunFloat64MulAndFloat64Add1 and friends.
           'cflags': ['-ffp-contract=off'],