build: Use {CFLAGS,CPPFLAGS, LDFLAGS}_FOR_BUILD for helper programs

Authored by dkg on Jul 16 2019, 7:00 PM.

Description

build: Use {CFLAGS,CPPFLAGS, LDFLAGS}_FOR_BUILD for helper programs

* doc/Makefile.am: add CPPFLAGS_FOR_BUILD for yat2m-for-build (other
flags were already present).
* src/Makefile.am: add {CFLAGS,CPPFLAGS,LDFLAGS}_FOR_BUILD for
mkhelper, mkw32errmap, and mkerrcodes.
  • Debian-bug-id: #932213
  • GnuPG-bug-id: T4643
  • Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>