--gprof make Emacs for profiling
--union-type define USE_LISP_UNION_TYPE (bad for GDB)
--malloc-check define GC_MALLOC_CHECK
- --no-mcheck dont define GC_MCHECK
+ --no-mcheck don't define GC_MCHECK
--wall compile with -Wall
--gcc3 use GCC 3.0 (30% slower compilation, slower code)
--trace-selection print traces in xselect.c