Update Linux gyp build to import and propagate external environment...

build/common.gypi

 # Copyright (c) 2009 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     # .gyp files should set chromium_code to 1 if they build Chromium-specific
     # code, as opposed to external code.  This variable is used to control
     # such things as the set of warnings to enable, and whether warnings are
     # treated as errors.
@@ skipping 113 matching lines @@
           '-pthread',
           '-march=pentium4',
           '-fno-exceptions',
           '-msse2',
           '-mfpmath=sse',
         ],
         'linkflags': [
           '-m32',
           '-pthread',
         ],
-        'scons_settings': {
-          'LIBPATH': ['$DESTINATION_ROOT/lib'],
+        'scons_variable_settings': {
+          'LIBPATH': ['$LIB_DIR'],
           # Linking of large files uses lots of RAM, so serialize links
           # using the handy flock command from util-linux.
           'FLOCK_LINK': ['flock', '$DESTINATION_ROOT/linker.lock', '$LINK'],
 
           # We have several cases where archives depend on each other in
           # a cyclic fashion.  Since the GNU linker does only a single
           # pass over the archives we surround the libraries with
           # --start-group and --end-group (aka -( and -) ). That causes
           # ld to loop over the group until no more undefined symbols
           # are found. In an ideal world we would only make groups from
           # those libraries which we knew to be in cycles. However,
           # that's tough with SCons, so we bodge it by making all the
           # archives a group by redefining the linking command here.
           #
           # TODO:  investigate whether we still have cycles that
           # require --{start,end}-group.  There has been a lot of
           # refactoring since this was first coded, which might have
           # eliminated the circular dependencies.
           'LINKCOM': [['$FLOCK_LINK', '-o', '$TARGET', '$LINKFLAGS', '$SOURCES', '$_LIBDIRFLAGS', '-Wl,--start-group', '$_LIBFLAGS', '-Wl,--end-group']],
           'SHLINKCOM': [['$FLOCK_LINK', '-o', '$TARGET', '$SHLINFLAGS', '$SOURCES', '$_LIBDIRFLAGS', '-Wl,--start-group', '$_LIBFLAGS', '-Wl,--end-group']],
           'IMPLICIT_COMMAND_DEPENDENCIES': 0,
         },
+        'scons_import_variables': [
+          'CC',
+          'CXX',
+          'LINK',
+        ],
+        'scons_propagate_variables': [
+          'CC',
+          'CCACHE_DIR',
+          'CXX',
+          'DISTCC_DIR',
+          'DISTCC_HOSTS',
+          'HOME',
+          'LINK',
+        ],
       },
     }],
     ['OS=="mac"', {
       'target_defaults': {
         'mac_bundle': 0,
         'xcode_settings': {
           'ALWAYS_SEARCH_USER_PATHS': 'NO',
           'GCC_C_LANGUAGE_STANDARD': 'c99',
           'GCC_CW_ASM_SYNTAX': 'NO',
           'GCC_DYNAMIC_NO_PIC': 'YES',
@@ skipping 130 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }