Previously this was inherited via PBD.
On MacOS/X, this adds
"-undefined dynamic_lookup -flat_namespace"
and various "-framework .." options to linkflags
Without this flag, .dylibs fail to link usually because
of missing `-lintl` (Undefined symbols: "_libintl_dgettext")
On other systems this is a NO-OP:
CFLAGS_OSX, CXXFLAGS_OSX and LINKFLAGS_OSX
are only set on the darwin platform.
The same source file cannot safely be used in different wscripts
with concurrency (if they were in the same wscript it works
.c.1.o .c.2.o, etc).
[387/764] c: libs/fst/vstwin.c -> build/libs/fst/vstwin.c.1.o
[731/764] c: libs/fst/vstwin.c -> build/libs/fst/vstwin.c.1.o
[746/764] cxxprogram: build/libs/fst/scanner.cc.1.o build/libs/fst/vstwin.c.1.o -> build/libs/fst/ardour-vst-scanner.exe
[750/764] cxxshlib: [...] build/libs/fst/vstwin.c.1.o [...] -> build/libs/ardour/ardour-3.dll
and about one every full moon (depending on concurrency) it failed:
missing file: 'build/libs/fst/vstwin.c.1.o'
