Fix build after previous commit.

pdfium.gyp

 {
   'variables': {
     'pdf_use_skia%': 0,
   },
   'target_defaults': {
     'defines' : [
       '_FXFT_VERSION_=2501',
       '_FPDFSDK_LIB',
       '_NO_GDIPLUS_',  # workaround text rendering issues on Windows
       'OPJ_STATIC',
@@ skipping 626 matching lines @@
         'core/src/fxge/fx_freetype/src/fxft_raster.c',
         'core/src/fxge/fx_freetype/src/fxft_sfnt.c',
         'core/src/fxge/fx_freetype/src/fxft_smooth.c',
         'core/src/fxge/fx_freetype/src/fxft_truetype.c',
         'core/src/fxge/fx_freetype/src/fxft_type1.c',
         'core/src/fxge/fx_freetype/src/fxft_type1cid.c',
         'core/src/fxge/ge/fx_ge.cpp',
         'core/src/fxge/ge/fx_ge_device.cpp',
         'core/src/fxge/ge/fx_ge_font.cpp',
         'core/src/fxge/ge/fx_ge_fontmap.cpp',
+        'core/src/fxge/ge/fx_ge_linux.cpp',
         'core/src/fxge/ge/fx_ge_path.cpp',
         'core/src/fxge/ge/fx_ge_ps.cpp',
         'core/src/fxge/ge/fx_ge_text.cpp',
         'core/src/fxge/ge/text_int.h',
       ],
       'conditions': [
         ['pdf_use_skia==1', {
           'sources': [
             'core/src/fxge/skia/fx_skia_blitter_new.cpp',
             'core/src/fxge/skia/fx_skia_device.cpp',
@@ skipping 191 matching lines @@
         'fpdfsdk/src/formfiller/FFL_ListBox.cpp',
         'fpdfsdk/src/formfiller/FFL_Notify.cpp',
         'fpdfsdk/src/formfiller/FFL_PushButton.cpp',
         'fpdfsdk/src/formfiller/FFL_RadioButton.cpp',
         'fpdfsdk/src/formfiller/FFL_TextField.cpp',
         'fpdfsdk/src/formfiller/FFL_Utils.cpp',
       ],
     },
   ],
 }