entd: Respect PKG_CONFIG variable if set in the environment.

This is required for the new cross-compilation support using pkg-config
wrappers instead of changing the pkg-config files themselves.

TEST=Compile entd on arm with and without PKG_CONFIG variable set.
     When the *.pc files don't have SYSROOT hardcoded into them,
     using the PKG_CONFIG wrapper ensures that we look in the board
     for libs instead of /usr/lib.

Change-Id: Iaff59b826aa059b7f6138de301004d82c763ac0d
Reviewed-on: http://gerrit.chromium.org/gerrit/2222
Reviewed-by: Chris Masone <cmasone@chromium.org>
Tested-by: David James <davidjames@chromium.org>
1 file changed