<OpenGL/gl3.h> does not exist there and -framework is not a gcc flag,
so the documented build line failed with no hint why. #+macosx picks
the header now, and both build lines are in the file -- pkg-config
carries the flags on either platform, apart from Apple's GL framework,
which has no pkg-config file to carry.
'#+' and '#-' introduce conditional compilation: the form that follows
is kept only when the feature expression is true, and otherwise is read
and thrown away. An expression is a feature name, or and / or / not
of them.
They are read time, not compile time.
Default features are the host's software-version, software-type and
machine-type as CHICKEN reports them, plus what --features flag adds.
1. Look for `compilation', not `compile' among the source
2. Read the file with provided --features from the (compilation ...)
form, then handle resulting file to sexc
compile-to-file returned process-wait's values and main dropped them,
so cc errors were printed, but then main compiler exited 0.
Also cleanup tmp C files when compilation failed.
Implement pub support for enums, and also anonymous enums declared
in-place.
Also give the cdr of a `pub' form the form's own location, so a
error about what follows `pub' can say where it was written
