[pmc] fix class WBs, detected by ZYROz

isa_pmc, freeze have a manual WBs
thawfinish, remove_attribute indirectly via build_attrib_index
name needs one for the write case
[pmc2c] fix del_namespace. require {} around WB return

there exist many methods without proper {} blocks for RETURN().

grep -B1 "RETURN(" src/pmc/*.pmc|grep -A1 "if "|grep -v "{"
such as:
src/pmc/namespace.pmc-        if (PMC_IS_NULL(ns))
src/pmc/namespace.pmc:            RETURN(void);
[codingstd] fix trailing whitespace

and remove one too much WB in pmclist.shift_pmc