Log message:
Simplified buildlink3.mk file by removing lines that attempted to include
the header file <rfuncs.h> through a compiler flag along with some
unnecessary linker flags. This should hopefully resolve pkg/27631,
security/gpgme dies on configure.

Log message:
Provides missing POSIX *_r functions: ttyname_r(), getenv_r() and
strerror_r(). These are thread safe versions of the corresponding functions
without the "_r".  The package is implemented so that it may be used simply
by including it's buildlink3.mk file.