reimplementation of usage requirements. Form is now:
boost_library(c
lib.cpp
STATIC_COMPILE_FLAGS ...
SHARED_COMPILE_FLAGS ...
STATIC_COMPILE_REQUIREMENTS ...
SHARED_COMPILE_REQUIREMENTS ...
DEPENDS a b d ...
)
where the shared/static "requirements" from a, b, d will be added to
the compile line for 'c' as appropriate. They're added in the order
they appear in the DEPENDS line. shared/static link requirements not
there yet.
Caveat #1: the CMakeLists for the DEPENDS must have already been
scanned! What exactly those compile requirements are must be known
already.
Caveat #2: the requirements don't recurse! Nothing in cmakeland
recurses. The list of DEPENDS must be exhaustive.
On the other hand, this does appear to reliably work.
