irep->pool[n].type should be IREP_TT_*, not MRB_TT_*

fix warning: "implicit conversion from enumeration type 'enum mrb_vtype' to different enumeration type 'enum irep_pool_type' [-Wenum-conversion]"

fix length check in read_section_debug()

Changed a variable declaration to top of block

Change supress to suppress

nextc(): always return an '\n' at end of input

fix #1564