Cleanup FX macros

This CL renames the FX_OS defines to have _OS_ in their names and drops
the _DESKTOP suffix. The FXM defines have been changed to just FX.

Change-Id: Iab172fba541713b5f6d14fb8098baf68e3364c74
Reviewed-on: https://pdfium-review.googlesource.com/14833
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>
diff --git a/fpdfsdk/javascript/PublicMethods.cpp b/fpdfsdk/javascript/PublicMethods.cpp
index ba42c3e..c065bd0 100644
--- a/fpdfsdk/javascript/PublicMethods.cpp
+++ b/fpdfsdk/javascript/PublicMethods.cpp
@@ -90,7 +90,7 @@
     pFormFillEnv->JS_appAlert(swMsg, nullptr, 0, 3);
 }
 
-#if _FX_OS_ != _FX_ANDROID_
+#if _FX_OS_ != _FX_OS_ANDROID_
 ByteString CalculateString(double dValue,
                            int iDec,
                            int* iDec2,
@@ -752,7 +752,7 @@
                                         const std::vector<CJS_Value>& params,
                                         CJS_Value& vRet,
                                         WideString& sError) {
-#if _FX_OS_ != _FX_ANDROID_
+#if _FX_OS_ != _FX_OS_ANDROID_
   if (params.size() != 6) {
     sError = JSGetStringFromID(IDS_STRING_JSPARAMERROR);
     return false;
@@ -994,7 +994,7 @@
                                          const std::vector<CJS_Value>& params,
                                          CJS_Value& vRet,
                                          WideString& sError) {
-#if _FX_OS_ != _FX_ANDROID_
+#if _FX_OS_ != _FX_OS_ANDROID_
   if (params.size() != 2) {
     sError = JSGetStringFromID(IDS_STRING_JSPARAMERROR);
     return false;