[kaffe] zlib.h checking with fastjar

[Kiyo Inaba]

Hi,

Thanks to improve using fastjar for kaffe. After this introduction, 
yesterday is the first time for my regression test. And I noticed,
one of my build environment does not have zlib.h installed.

And of course configure script checks this as
 checking zlib.h usability... no
 checking zlib.h presence... no
 checking for zlib.h... no
but, the build process continues and failed in compilation as
 make[4]: Entering directory `/proj/kaffe/kaffe-snap-060112-m68k-linux-i/external/gcc/fastjar'
 source='jartool.c' object='fastjar-jartool.o' libtool=no \
 DEPDIR=.deps depmode=gcc /bin/sh ../../../../kaffe-snap-060112/external/gcc/fastjar/scripts/depcomp \
 gcc -DHAVE_CONFIG_H -I. -I../../../../kaffe-snap-060112/external/gcc/fastjar -I.  -I. -I../../../../kaffe-snap-060112/external/gcc/fastjar -I../zlib/ -I../../../../kaffe-snap-060112/external/gcc/fastjar/../include -DWITH_SHIFT_DOWN  -W -Wall -pedantic -Wstrict-prototypes -Wmissing-prototypes -Wwrite-strings -I../../../../kaffe-snap-060112/external/gcc/fastjar/../../../replace -I./../../../replace -g -O2 -Wall -W -O1 -fno-omit-frame-pointer -pthread -c -o fastjar-jartool.o `test -f 'jartool.c' || echo '../../../../kaffe-snap-060112/external/gcc/fastjar/'`jartool.c
 ../../../../kaffe-snap-060112/external/gcc/fastjar/jartool.c:195: zlib.h: No such file or directory
 make[4]: *** [fastjar-jartool.o] Error 1
 make[4]: Leaving directory `/proj/kaffe/kaffe-snap-060112-m68k-linux-i/external/gcc/fastjar'

Has it becomes mandatory to have zlib when we use fastjar? It looks like
zlib.h (and other files) are in external/gcc/zlib, and possibly it can
be used.

Kiyo