Export PACKAGES as an environment variable breaks libbluray

[lantw44]

When using portmaster to install the multimedia/libbluray port, the Requires.private line in libbluray.pc is broken because the configure script of libbluray appends things to PACKAGES variable and set the value of Requires.private to PACKAGES when generating libbluray.pc.

libbluray.pc installed by typing make install:

Requires.private:  libxml-2.0 freetype2 fontconfig

libbluray.pc installed by portmaster:

Requires.private: /usr/ports/packages libxml-2.0 freetype2 fontconfig

The latter one causes gvfs to fail to find libbluray because pkg-config doesn't know what /usr/ports/packages is:

$ pkg-config --cflags libbluray
Package /usr/ports/packages was not found in the pkg-config search path.
Perhaps you should add the directory containing `/usr/ports/packages.pc'
to the PKG_CONFIG_PATH environment variable
Package '/usr/ports/packages', required by 'libbluray', not found