implements macro version of isblank(3) and increase _ctype_ table 8bit -> 16bit.

[Takehiko NOZAKI]

https://mail-index.netbsd.org/tech-userlevel/2011/03/21/msg004737.html

• change ctype table in ctype.h and gen/ctype_.c 8bit -> 16 or 32bit. it's insufficient bitwidth to implement all ctype class. see isblank's comment in ctype.h. (http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/shlib_version)

our ctype.h doesn't supply macro version of isblankI(3). because ctype table is 8bit, it can not afford to reserve a bit for blank character. (isblank is frequently called from shell, editor and so on, providing macro version is important, i think)

[Takehiko NOZAKI]

in NetBSD-current, my patch was merged, but messed up with bikesched.

[Takehiko NOZAKI]

beware, this change is not MFC(merge from -current), why difference? because:

• ctype_bits.h rev1.2 change(Prefix ctype bitmask macros with _CTYPE) is stupid change that breaks build of vanila libstdc++, so i revert it.
• make _CTYPE prefix is only for new 16 bit table's bit.
• the change from BUILDCOLD to BUILD_LEGACY Makefile knob in -current is completely stupid change.
• BUILDCOLD trick aims to build libc.so.12 and libc.so.13 from same source tree.
• but BULD_LEGACY is only deletion mark after bumping libc.so.13.

[Takehiko NOZAKI]

done, see <<cset 62cbb86f288cb60026f7b24f3a58d2f492c20ae1>>.