cmake: add MODULE linker flags

Otherwise cmake appears to fall back to using the EXE linker flags,
which results in non-working shared-objects as they are treated
as binaries and are linked at the usual entry-point address.

Issue #52.

share/goa/lib/build/cmake.tcl

@@ -27,6 +27,7 @@ proc create_or_update_build_dir { } {
 	lappend cmd "-DCMAKE_CXX_FLAGS='$cxxflags $cppflags'"
 	lappend cmd "-DCMAKE_EXE_LINKER_FLAGS='$ldflags $ldlibs_common $ldlibs_exe'"
 	lappend cmd "-DCMAKE_SHARED_LINKER_FLAGS='$ldflags_so $ldlibs_common $ldlibs_so'"
+	lappend cmd "-DCMAKE_MODULE_LINKER_FLAGS='$ldflags_so $ldlibs_common $ldlibs_so'"
 	lappend cmd "-DCMAKE_INSTALL_PREFIX:PATH=[file join $build_dir install]"
 
 	if {[info exists cmake_quirk_args]} {