tools: add support for additional items in .pc files for local builds

tools: add support for additional items in .pc files for local builds

Some libraries require different compiler-flags when being used in a
local build compared to a build using installed libraries.

Reflect that by supporting local cflags variables in generated
pkg-config files. The local variants will be empty in the installed
pkg-config files.

The flags for the linker in the local variants will have to specify
the search patch for the library with "-Wl,-rpath-link=", while the
flags for the installed library will be "-L".

Add needed directory patterns.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>