bugfix: problem in build system (especially when cross-compiling)

Thanks to Tomas Heinrich and winfried_mb2@xmsnet.nl for the patch.
closes: http://bugzilla.adiscon.com/show_bug.cgi?id=445
prepare for 7.3.15 release
bugfix: potential hang *in debug mode* on rsyslogd termination
Imjournal state files can be stored in WorkDirectory

When the imjournal state file path doesn't start with '/',
then it's by default stored in WorkDirectory. When path
starts with '/', full path is used.
Drop unneeded macro definition

The macro itself was a malformed version of "_GNU_SOURCE" and thus had
no effect. It is not needed as this macro is already defined
via AC_GNU_SOURCE.
Clean up warnings in imjournal and omjournal
Don't #include libestr and libee headers when not necessary

Through msg.h, many unrelated components needlessly required
LIBEE_CFLAGS.
Revert "bugfix: problem in build system (especially when cross-compiling)"

This reverts commit 813c9c7f524976ef598864afbb729bca31557c32.

Removing references to libee.h in the previous commit solves the build
issue so the cflag shoudn't be needed after all.
Remove redundat cflags and links to libraries

This prevents linking with libee, liblognorm and libgcrypt when not
necessary.