[PATCH v4] pkg-config and installcheck improvements

[JereLeppanen]

Rework pkg-config files so that application can link libodp and libodphelper statically with pkg-config --static, without the -static linker option.

Don't run test suites in installcheck. Instead build and run a minimal test application. This saves a lot of time in distcheck, since tests are not run twice. It's also a better test, since currently installcheck doesn't build an application against the installed headers and libraries, but just re-runs the tests built earlier in make all.

Do installcheck in CI build jobs.

v2:

• Rebase.
• Add explanation in internal pc file.

v3:

• Add review tags.

v4:

• Rebase.
• Fix library name in test/miscellaneous/Makefile.am.