scons: set LD_LIBRARY_PATH for actions, similarly to the make build
scons: set LD_LIBRARY_PATH for actions, similarly to the make build

This allows shared libraries to be installed into <(SHARED_LIB_DIR) and have
build tools find them

Review URL: http://codereview.chromium.org/378007
old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google