build: Fix pkg-config generation on local build

When building with internal dependencies (subprojects) meson fails to
configure the build with the following message:
"""
meson.build:84:20: ERROR: requires argument not a string, library with
pkgconfig-generated file or pkgconfig-dependency object, got
<InternalDependency dep140431893321616: True>
"""
Use libraries instead of requires when calling pkgconfig.generate() to
make the configuration succeed.

Change-Id: I48e0c6bd625af8d10fecf6235b9d034453abf9d6
Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
1 file changed