[gn] Migrate more custom cflags from gyp to gn

test/cctest/BUILD.gn

Index: test/cctest/BUILD.gn
diff --git a/test/cctest/BUILD.gn b/test/cctest/BUILD.gn
index 71e9eb0d2c0296a68f3a22a1b416efea04cb9f18..daf59705922ea0e2ca3501ffee414e0f444f8f9f 100644
--- a/test/cctest/BUILD.gn
+++ b/test/cctest/BUILD.gn
@@ -14,9 +14,7 @@ gypi_values = exec_script("//build/gypi_to_gn.py",
 v8_executable("cctest") {
   testonly = true
 
-  sources = [
-    "$target_gen_dir/resources.cc",
-  ] + gypi_values.cctest_sources
+  sources = [ "$target_gen_dir/resources.cc" ] + gypi_values.cctest_sources
 
   if (v8_current_cpu == "arm") {
     sources += gypi_values.cctest_sources_arm
@@ -47,13 +45,6 @@ v8_executable("cctest") {
     sources += [ "test-platform-linux.cc" ]
   } else if (is_win) {
     sources += [ "test-platform-win32.cc" ]
-    # TODO(machenbach): Translate from gyp.
-    # "msvs_settings": {
-    #   "VCCLCompilerTool": {
-    #     # MSVS wants this for gay-{precision,shortest}.cc.
-    #     "AdditionalOptions": ["/bigobj"],
-    #   },
-    # },
   }
 
   configs = [
@@ -62,15 +53,6 @@ v8_executable("cctest") {
   ]
 
   # TODO(machenbach): Translate from gyp.
-  #['v8_current_cpu=="ppc" or v8_current_cpu=="ppc64" \
-  #  or v8_current_cpu=="arm" or v8_current_cpu=="arm64" \
-  #  or v8_current_cpu=="s390" or v8_current_cpu=="s390x"', {
-  #  # disable fmadd/fmsub so that expected results match generated code in
-  #  # RunFloat64MulAndFloat64Add1 and friends.
-  #  'cflags': ['-ffp-contract=off'],
-  #}],
-
-  # TODO(machenbach): Translate from gyp.
   #["OS=="aix"", {
   #  "ldflags": [ "-Wl,-bbigtoc" ],
   #}],
@@ -90,15 +72,29 @@ v8_executable("cctest") {
     deps += [ "../..:v8" ]
   }
 
+  cflags = []
+  ldflags = []
+
+  if (v8_current_cpu == "ppc" || v8_current_cpu == "ppc64" ||
+      v8_current_cpu == "arm" || v8_current_cpu == "arm64" ||
+      v8_current_cpu == "s390" || v8_current_cpu == "s390x") {
+    # Disable fmadd/fmsub so that expected results match generated code in
+    # RunFloat64MulAndFloat64Add1 and friends.
+    cflags += [ "-ffp-contract=off" ]
+  }
+
   if (is_win) {
     # This warning is benignly triggered by the U16 and U32 macros in
     # bytecode-utils.h.
     # C4309: 'static_cast': truncation of constant value
-    cflags = [ "/wd4309" ]
+    cflags += [ "/wd4309" ]
+
+    # MSVS wants this for gay-{precision,shortest}.cc.
+    cflags += [ "/bigobj" ]
 
     # Suppress warnings about importing locally defined symbols.
     if (is_component_build) {
-      ldflags = [
+      ldflags += [
         "/ignore:4049",
         "/ignore:4217",
       ]