Update Linux gyp build to import and propagate external environment

variables ($CC, $DISTCC_DIR, $HOME, etc.).
Accomodate spelling change ($CHROME_SRC_DIR => $SRC_DIR) that
makes the gyp SCons a little more generic.
Use the new $LIB_DIR variable the gyp SCons generator now defines for us.
Review URL: http://codereview.chromium.org/42650

git-svn-id: http://src.chromium.org/svn/trunk/src/build@12583 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

SConscript.main

@@ -86,6 +86,7 @@ root_env = Environment(
     all_system_libs = [],
 
     CHROME_SRC_DIR = '$MAIN_DIR/..',
+    SRC_DIR = '$MAIN_DIR/..',
     DESTINATION_ROOT = '$MAIN_DIR/$BUILD_TARGET_DIR',
 
     # Where ComponentTestProgram() will build test executables.
@@ -775,6 +776,7 @@ for env in environment_list:
   # resolving these over and over again.
   env.Replace(
       CHROME_SRC_DIR        = str(env.Dir('$CHROME_SRC_DIR')),
+      SRC_DIR               = str(env.Dir('$SRC_DIR')),
       DESTINATION_ROOT      = str(env.Dir('$DESTINATION_ROOT')),
       TARGET_ROOT           = str(env.Dir('$TARGET_ROOT')),
       OBJ_ROOT              = str(env.Dir('$OBJ_ROOT')),

common.gypi

@@ -131,8 +131,8 @@
           '-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'],
@@ -155,6 +155,20 @@
           '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"', {