configure --with-osmesa fails to link

[Peter Urbanec]

I just turned on --with-osmesa and configure fails for me:

> checking for -lOSMesa... not found
> configure: error: libOSMesa development files not found (or too old), 
> OpenGL rendering in bitmaps won't be supported.
> This is an error since --with-osmesa was requested

config.log output would suggest that perhaps the test is being treated 
as C code, but libOSMesa needs to link with C++ libs.

> configure:9067: checking for -lOSMesa
> configure:9092: gcc -o conftest  -g3 -feliminate-unused-debug-symbols 
> -O0 -mtune=core2    conftest.c -lOSMesa   -lSM -lICE -lXext -lX11 
> -lm   >&5
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `operator delete[](void*)'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `operator new(unsigned long)'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `_glapi_get_proc_address'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `operator delete(void*)'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `_glapi_get_dispatch_table_size'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `operator new[](unsigned long)'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `__cxa_pure_virtual'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `__gxx_personality_v0'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `_glapi_get_context'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `vtable for __cxxabiv1::__vmi_class_type_info'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `vtable for __cxxabiv1::__class_type_info'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `_glapi_add_dispatch'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `_glapi_check_multithread'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `_glapi_tls_Context'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `_glapi_set_context'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `vtable for __cxxabiv1::__si_class_type_info'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `_glapi_set_dispatch'
> /usr/lib/gcc/x86_64-pc-linux-gnu/4.6.3/../../../../lib64/libOSMesa.so: 
> undefined reference to `_glapi_tls_Dispatch'
> collect2: ld returned 1 exit status

This is on Gentoo x64 with:

media-libs/mesa-8.1_rc1_pre20120814
     (classic egl g3dvl gallium llvm nptl osmesa shared-glapi vdpau xvmc 
-bindist -d3d -debug -gbm -gles1 -gles2 -kernel_FreeBSD -openvg 
-pax_kernel -pic -r600-llvm-compiler -selinux -video_cards_i915 
-video_cards_i965 -video_cards_intel -video_cards_nouveau 
-video_cards_r100 -video_cards_r200 -video_cards_r300 -video_cards_r600 
-video_cards_radeon -video_cards_radeonsi -video_cards_vmware -wayland 
-xa -xorg)

sys-devel/gcc-4.6.3
     (cxx fortran graphite mudflap multilib nls nptl openmp -altivec 
-bootstrap -build -doc -fixed-point -gcj -go -gtk -hardened -libssp 
-multislot -nocxx -nopie -nossp -objc -objc++ -objc-gc -test -vanilla)

Any suggestions as to how this could be fixed? My autoconf skills are no 
match for this problem :-(

Thanks.