Modify big integer library

pdfium.gyp

 {
   'variables': {
     'pdf_use_skia%': 0,
   },
   'target_defaults': {
     'defines' : [
       'FOXIT_CHROME_BUILD',
       '_FXFT_VERSION_=2501',
       '_FPDFSDK_LIB',
       '_NO_GDIPLUS_',  # workaround text rendering issues on Windows
@@ skipping 18 matching lines @@
     'msvs_disabled_warnings': [
       4005, 4018, 4146, 4333, 4345, 4267
     ],
   },
   'targets': [
     {
       'target_name': 'pdfium',
       'type': 'static_library',
       'dependencies': [
         'safemath',
+        'bigint',
         'fdrm',
         'fpdfdoc',
         'fpdfapi',
         'fpdftext',
         'formfiller',
         'fxcodec',
         'fxcrt',
         'fxedit',
         'fxge',
         'javascript',
@@ skipping 81 matching lines @@
         'third_party/logging.h',
         'third_party/macros.h',
         'third_party/template_util.h',
         'third_party/numerics/safe_conversions.h',
         'third_party/numerics/safe_conversions_impl.h',
         'third_party/numerics/safe_math.h',
         'third_party/numerics/safe_math_impl.h',
       ],
     },
     {
+      'target_name': 'bigint',
+      'type': 'static_library',
+      'sources': [
+        'third_party/bigint/BigInteger.hh',
+        'third_party/bigint/BigIntegerLibrary.hh',
+        'third_party/bigint/BigIntegerUtils.hh',
+        'third_party/bigint/BigUnsigned.hh',
+        'third_party/bigint/NumberlikeArray.hh',
+        'third_party/bigint/BigUnsignedInABase.hh',
+        'third_party/bigint/BigInteger.cc',
+        'third_party/bigint/BigIntegerUtils.cc',
+        'third_party/bigint/BigUnsigned.cc',
+        'third_party/bigint/BigUnsignedInABase.cc',
+      ],
+    },
+    {
       'target_name': 'fdrm',
       'type': 'static_library',
       'ldflags': [ '-L<(PRODUCT_DIR)',],
       'sources': [
         'core/include/fdrm/fx_crypt.h',
         'core/src/fdrm/crypto/fx_crypt.cpp',
         'core/src/fdrm/crypto/fx_crypt_aes.cpp',
         'core/src/fdrm/crypto/fx_crypt_sha.cpp',
       ],
     },
@@ skipping 686 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',
       ],
     },
   ],
 }