Add support for --enable-target-optspace to compile with -Os instead of -O2,...

Add support for --enable-target-optspace to compile with -Os instead of -O2, and default m32r to use it


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@19374 138bc75d-0d04-0410-961f-82ee72b054a4