makefile: fix exports of PKG_CONFIG_LIBDIR for pkg-config calls

The parenthesis pushed the exports into a subshell thus made them useless.

Corresponding to flashrom svn r1910.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
1 file changed