libgpg-error, libgcrypt, libassuan, gpgme and libksba don't allow 'make check' with building the particular library.
(npth does.)
This is due to having `AM_LDFLAGS = -no-install` in `tests/Makefile.am`.
If it's good to support 'make check' with not-yet-installed library, let us remove the line. Doing this, it will work even if rpath doesn't work well.
I know that it's only the particular library in questions. When we do for libraries, installing them is required.