Remove AC_CANONICAL_HOST and AC_GNU_SOURCE.

Adding AC_GNU_SOURCE isn't recommended, and our only use of
AC_CANONICAL_HOST (to calculate the rpath flag) should be done by the
build environment, and is likely incomplete anyway.

Makefile.in

@@ -98,8 +98,7 @@ CPPFLAGS+=	-I. -I${LOCALBASE}/include
 
 LDFLAGS+=	@LDFLAGS@
 
-LDADD+=		-L${LOCALBASE}/lib @RPATH@,${LOCALBASE}/lib	\
-		-lbz2 -lz -larchive @LIBS@
+LDADD+=		-L${LOCALBASE}/lib -lbz2 -lz -larchive @LIBS@
 LDADD+=		-lsqlite3
 
 CLEANFILES+=	${DPSRCS}

config.h.in

@@ -153,38 +153,6 @@
 /* Define to 1 if you have the ANSI C header files. */
 #undef STDC_HEADERS
 
-/* Enable extensions on AIX 3, Interix.  */
-#ifndef _ALL_SOURCE
-# undef _ALL_SOURCE
-#endif
-/* Enable GNU extensions on systems that have them.  */
-#ifndef _GNU_SOURCE
-# undef _GNU_SOURCE
-#endif
-/* Enable threading extensions on Solaris.  */
-#ifndef _POSIX_PTHREAD_SEMANTICS
-# undef _POSIX_PTHREAD_SEMANTICS
-#endif
-/* Enable extensions on HP NonStop.  */
-#ifndef _TANDEM_SOURCE
-# undef _TANDEM_SOURCE
-#endif
-/* Enable general extensions on Solaris.  */
-#ifndef __EXTENSIONS__
-# undef __EXTENSIONS__
-#endif
-
-
-/* Define to 1 if on MINIX. */
-#undef _MINIX
-
-/* Define to 2 if the system does not provide POSIX.1 features except with
-   this defined. */
-#undef _POSIX_1_SOURCE
-
-/* Define to 1 if you need to in order for `stat' and other things to work. */
-#undef _POSIX_SOURCE
-
 /* Define for Solaris 2.5.1 so the uint64_t typedef from <sys/synch.h>,
    <pthread.h>, or <semaphore.h> is not used. If the typedef were allowed, the
    #define below would cause a syntax error. */