The build eventually dies with the following output.  I tried to get -m32 in the right *FLAGS from configure.ac, but the Gallium build goes to great lengths to remove everything you set from there.

g++  -L/usr/lib64/llvm  -lpthread -lffi -ldl -lm  lp_test_format.o lp_test_main.o -o lp_test_format -Wl,--start-group  -L../../auxiliary/ -lgallium libllvmpipe.a -lLLVMpic16passes -lLLVMMCDisassembler -lLLVMXCoreCodeGen -lLLVMXCoreAsmPrinter -lLLVMXCoreInfo -lLLVMSystemZCodeGen -lLLVMSystemZAsmPrinter -lLLVMSystemZInfo -lLLVMSparcCodeGen -lLLVMSparcAsmPrinter -lLLVMSparcInfo -lLLVMPowerPCCodeGen -lLLVMPowerPCAsmPrinter -lLLVMPowerPCInfo -lLLVMPIC16AsmPrinter -lLLVMPIC16CodeGen -lLLVMPIC16Info -lLLVMMipsAsmPrinter -lLLVMMipsCodeGen -lLLVMMipsInfo -lLLVMMSP430CodeGen -lLLVMMSP430AsmPrinter -lLLVMMSP430Info -lLLVMMBlazeAsmPrinter -lLLVMMBlazeCodeGen -lLLVMMBlazeInfo -lLLVMLinker -lLLVMipo -lLLVMInterpreter -lLLVMInstrumentation -lLLVMJIT -lLLVMExecutionEngine -lLLVMCppBackend -lLLVMCppBackendInfo -lLLVMCellSPUCodeGen -lLLVMCellSPUAsmPrinter -lLLVMCellSPUInfo -lLLVMCBackend -lLLVMCBackendInfo -lLLVMBlackfinCodeGen -lLLVMBlackfinAsmPrinter -lLLVMBlackfinInfo -lLLVMBitWriter -lLLVMX86Disassembler -lLLVMX86AsmParser -lLLVMX86CodeGen -lLLVMX86AsmPrinter -lLLVMX86Info -lLLVMAsmParser -lLLVMARMDisassembler -lLLVMARMAsmParser -lLLVMARMCodeGen -lLLVMARMAsmPrinter -lLLVMARMInfo -lLLVMArchive -lLLVMBitReader -lLLVMAlphaCodeGen -lLLVMSelectionDAG -lLLVMAlphaAsmPrinter -lLLVMAsmPrinter -lLLVMMCParser -lLLVMCodeGen -lLLVMScalarOpts -lLLVMInstCombine -lLLVMTransformUtils -lLLVMipa -lLLVMAnalysis -lLLVMTarget -lLLVMMC -lLLVMCore -lLLVMAlphaInfo -lLLVMSupport -lLLVMSystem -lstdc++  -L/opt/xorg-master-x86_64/lib -lX11 -lXext -lXdamage -lXfixes -lXxf86vm   -L/opt/xorg-master-x86_64/lib -ldrm   -lm -lpthread -ldl -Wl,--end-group
/usr/bin/ld: skipping incompatible ../../auxiliary//libgallium.a when searching for -lgallium
/usr/bin/ld: cannot find -lgallium
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libX11.so when searching for -lX11
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libX11.a when searching for -lX11
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libX11.so when searching for -lX11
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libX11.a when searching for -lX11
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXext.so when searching for -lXext
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXext.a when searching for -lXext
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXext.so when searching for -lXext
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXext.a when searching for -lXext
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXdamage.so when searching for -lXdamage
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXdamage.a when searching for -lXdamage
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXdamage.so when searching for -lXdamage
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXdamage.a when searching for -lXdamage
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXfixes.so when searching for -lXfixes
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXfixes.a when searching for -lXfixes
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXfixes.so when searching for -lXfixes
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXfixes.a when searching for -lXfixes
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXxf86vm.so when searching for -lXxf86vm
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXxf86vm.a when searching for -lXxf86vm
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXxf86vm.so when searching for -lXxf86vm
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libXxf86vm.a when searching for -lXxf86vm
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libdrm.so when searching for -ldrm
/usr/bin/ld: skipping incompatible /opt/xorg-master-x86_64/lib/libdrm.so when searching for -ldrm
collect2: ld returned 1 exit status
gmake[4]: *** [lp_test_format] Error 1

I'd like to avoid breaking the Gallium build, but I can't do that if I can't get it to build.  There's irony there somewhere.