[imcc] micro optimizations

ask for DEBUG_OPT1 & imcc->debug before doing 3 calls
inline imcc_vfprintf
[immc] Fixed -O1. Special-case get_global for branch_cond_loop_swap [GH #1037]

See https://github.com/parrot/parrot/issues/1037 for the nci problem.
I couldn't see any logical problem with the attempted optimization

add I0,1 vs inc I0 tested ok.
just a get_global_p with if_p_ic P4,out converted to unless_p_ic P4,loop
was problematic, so we skip optimizing such loops.
get_global has no type attached, so we need to STREQ

added a IMCC_debug DEBUG_OPT1 notice for this case.