Fix GNU classpath build on x86_64

The issue was that early x86-64 linuxes only provided a 64bit GTk. As we compile with -m32 we need a 32bit GTk to link against. This often wasn't present on early x86-64 linuxes so we disabled the GTk peers. IIRC Dave Grove was interested in re-enabling this option too.

Doesn't work for me on the machines at Watson (RHEL5.1 x86_64). I've got (as far as I can tell) all of the 32 bit versions of the libraries (libcario, etc) installed in the standard places in addition to the 64bit versions, but the classpath build process doesn't seem to find them. It gets stuck wanting to link to the 64 bit versions.

[exec] 5932 problems (5932 warnings)/usr/bin/ld: skipping incompatible /usr/lib64/libgtk-x11-2.0.so when searching for -lgtk-x11-2.0
[exec] /usr/bin/ld: skipping incompatible /usr/lib64/libgdk-x11-2.0.so when searching for -lgdk-x11-2.0
[exec] /usr/bin/ld: skipping incompatible /usr/lib64/libatk-1.0.so when searching for -latk-1.0
[exec] /usr/bin/ld: skipping incompatible /usr/lib64/libpangocairo-1.0.so when searching for -lpangocairo-1.0
[exec] /usr/bin/ld: skipping incompatible /usr/lib64/libcairo.so when searching for -lcairo
[exec] /usr/bin/ld: skipping incompatible /usr/lib64/libcairo.so when searching for -lcairo
[exec] /usr/bin/ld: cannot find -lcairo
[exec] collect2: ld returned 1 exit status
[exec] make[3]: *** [libgtkpeer.la] Error 1
[exec] make[3]: Leaving directory `/home/dgrove/buildit/rvm-trunk/components/classpath/97.1p1/classpath/native/jni/gtk-peer'
[exec] make[2]: *** [all-recursive] Error 1
[exec] make[2]: Leaving directory `/home/dgrove/buildit/rvm-trunk/components/classpath/97.1p1/classpath/native/jni'
[exec] make[1]: *** [all-recursive] Error 1
[exec] make[1]: Leaving directory `/home/dgrove/buildit/rvm-trunk/components/classpath/97.1p1/classpath/native'
[exec] make: *** [all-recursive] Error 1

BUILD FAILED
/home/dgrove/buildit/rvm-trunk/build.xml:183: The following error occurred while executing this line:
/home/dgrove/buildit/rvm-trunk/build/components/classpath.xml:247: The following error occurred while executing this line:
/home/dgrove/buildit/rvm-trunk/build/components/base.xml:70: The following error occurred while executing this line:
/home/dgrove/buildit/rvm-trunk/build/components/base.xml:76: The following error occurred while executing this line:
/home/dgrove/buildit/rvm-trunk/build/components/classpath.xml:209: exec returned: 2

Looking for the libs via find:

[dgrove@legato /usr]$ find . -name "libgdk-x11*"
./lib64/libgdk-x11-2.0.so
./lib64/libgdk-x11-2.0.so.0.1000.4
./lib64/libgdk-x11-2.0.so.0
./lib/libgdk-x11-2.0.so
./lib/libgdk-x11-2.0.so.0.1000.4
./lib/libgdk-x11-2.0.so.

some googling suggests we should be using linux32 instead of -m32. I haven't tried to whack the ant scripts to do this, but maybe someone could take a look.

I can't see the linux32 option in GCC, the references I find still refer to -m32. As we're building with ant Filip can override the option not to compile the GTk peers on x86_64 using the following:
cp.enable.gtk-peer=" --enable-gtk-peer"
maybe we should provide another hook to do this and properly document it.

linux32 is a command.

It looks like perhaps we'd need to wrap the whole invocation of the GNU classpath build as args to linux32 and possibly drop the -m32 args to gcc. I haven't had a chance to play with this yet.

Rescheduling for 2.9.4. Ideally a proper x86_64 build will supersede this issue. But investigating using linux32 can be done in the 2.9.4 time frame.

Less than 1 week to 3.0.1; pushing off more items to 3.0.2. Move back if you disagree and/or have time to tackle the issue.

Defer to 3.1.1

bulk defer open issues to 3.1.2