Add -I../.. -L../.. to CFLAGS for minizip and miniunzip.

Add -I../.. -L../.. to CFLAGS for minizip and miniunzip.

Trying to build miniunzip utility from contrib/minizip after an
autoreconf -f produces

	[...]
	In file included from minizip.c:61:0:
	zip.h:50:18: fatal error: zlib.h: No such file or directory

unless zlib is already installed.  Use AM_CFLAGS to set the include
path and library path to point to the just-build copy of zlib to
fix this.  (This was already done for libminizip but not the binaries
that use it before this patch.)