[gentoo-dev] new helper: econf_build

[Mike Frysinger]

i've found myself a few times having to implement logic like so:
	CFLAGS=${BUILD_CFLAGS:--O1 -pipe} \
	CXXFLAGS=${BUILD_CXXFLAGS:--O1 -pipe} \
	CPPFLAGS=${BUILD_CPPFLAGS} \
	LDFLAGS=${BUILD_LDFLAGS} \
	CC=$(tc-getBUILD_CC) \
	LD=$(tc-getBUILD_LD) \
	econf --host=${CBUILD} "$@"

this is to deal with packages that build up not insignificant (let's call them 
"nificant") binaries which are then used at build time.  when cross-compiling, 
you can't execute those binaries, and things fail.

python is a good example.  it builds up the local python interpreter (which is 
all written in C/etc...), and then uses that to parse local python scripts 
which take care of building everything else.  so a while ago we added code so 
that it'd build two python binaries when cross-compiling: a local ${CBUILD} 
version which is then used to parse the python build files to compile for 
${CHOST}.  using host python won't work if it's newer/older/insane/afk.

ncurses compiles its local term database by first creating a tic helper and 
then parsing its local files.  we can't use the build system's tic because if 
the installed ncurses is a different version, we run into fun things like 
crashes/infinite loops/etc...

the latest thing i hit was elfutils where it creates a local binary to 
generate a database of headers which it then compiles into the target code.

so rather than continuing to copy & paste this logic everywhere, i'm going to 
add it to toolchain-funcs.eclass as "econf_build".  any feedback before i do ?
-mike