Fuse an app's native-compiled numeric-leaf fns plus its source into one
static executable: no sidecar .so, no toolchain on the target. The AOT path
(#148) already produced a prebuilt module + manifest; this links them into
the jpm-built exe so the app ships as a single file.
`jolt cgen-build -m NS -o OUT` stages a build dir (src/jolt-core symlinks
into the jolt tree, a generated cg.c of the hot fns, an uberscript bundle of
the app, and an entry that bakes the runtime, installs the native fns as var
roots, and runs -main), then runs `jpm build` there — declare-native builds
cg.a and declare-executable static-links it (jpm's create-executable marshals
the module cfns and calls its static entry at startup).
Build needs cc + jpm; the result needs neither. Mechanics that bit, codified
in cgen_build.janet: stdlib_embed slurps .clj cwd-relative so the build runs
in a repo-mirroring dir; jpm hardcodes ./project.janet and sets syspath=modpath;
the executable's dofile imports cg and static-links cg.a, neither ordered nor
release-built by default, so deps are wired explicitly; cleanup must lstat (the
tree symlinks must not be followed); the inner build runs --workers=1 so it
doesn't starve siblings in the parallel gate.
test/integration/cgen-build-test.janet builds the mandelbrot fixture, runs it
from a clean dir with no src/ and no cg.so, and checks the total at native
speed. Closes jolt-a7ds.
Co-authored-by: Yogthos <yogthos@gmail.com>