In linux and mac, use Arial to replace Tahoma for displaying east europe characters

BUG=

Review URL: https://codereview.chromium.org/301263002

fpdfsdk/src/pdfwindow/PWL_FontMap.cpp

diff --git a/fpdfsdk/src/pdfwindow/PWL_FontMap.cpp b/fpdfsdk/src/pdfwindow/PWL_FontMap.cpp
index c656f0c..b5f5002 100644
--- a/fpdfsdk/src/pdfwindow/PWL_FontMap.cpp
+++ b/fpdfsdk/src/pdfwindow/PWL_FontMap.cpp
@@ -508,7 +508,11 @@
 	{ SHIFTJIS_CHARSET, "MS Gothic" },
 	{ HANGUL_CHARSET, "Batang" },
 	{ RUSSIAN_CHARSET, "Arial" },
+#if _FXM_PLATFORM_ == _FXM_PLATFORM_LINUX_ || _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
+	{ EASTEUROPE_CHARSET, "Arial" },
+#else
 	{ EASTEUROPE_CHARSET, "Tahoma" },
+#endif
 	{ ARABIC_CHARSET, "Arial" },
 	{ -1, NULL }
 };