Unignore most warnings on POSIX in build/SConscript.main.

third_party/icu38/SConscript

 # Copyright 2008, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #    * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #    * Redistributions in binary form must reproduce the above
@@ skipping 49 matching lines @@
 if env['PLATFORM'] == 'win32':
   env.Append(
       CCFLAGS = [
           '/WX',
       ]
   )
 else:
   env.Append(
       CCFLAGS = [
           '-Wno-parentheses',
+
+          # see uprv_UnicodeStringDummy at end of source/common/unistr.cpp
+          '-Wno-unused-function'
       ]
   )
 
 if 'WIN32_LEAN_AND_MEAN' in env['CPPDEFINES']:
   env['CPPDEFINES'].remove('WIN32_LEAN_AND_MEAN')
 
 input_files = [
     'source/common/bmpset.cpp',
     'source/common/brkeng.cpp',
     'source/common/brkiter.cpp',
@@ skipping 267 matching lines @@
 
 env.ChromeStaticLibrary('icuuc', cpp_object_files +
                            c_object_files +
                            stray_object_files)
 
 # On Windows the ICU data is built into a DLL.  On Linux, install the .dat file.
 if env['PLATFORM'] == 'win32':
   env.Install('$OBJ_ROOT', 'icudt38.dll')
 else:
   env.Install('$OBJ_ROOT', 'source/data/in/icudt38l.dat')