Now that we assume pthreads, the only assembly left is in libmp and libsec. We only ever added assembly for 386. The portable C code is fine for plan9port.

If mk gets into a bad state, it's not obvious that you can remove the binary to force the rebuild. Also, not rebuilding means that bugs in mkmk.sh are not noticed. Just rebuild from scratch every time. It doesn't take too long compared to the rest of INSTALL.

Linux 2.4 is dead. (The libthread code hasn't worked for Linux 2.4 for a long time.)

Fixes #334.

FreeBSD 11.2 by default does not have gcc.

My MacBook Pro has hw.ncpu=12, so set NPROC=12. Speeds up INSTALL dramatically. Should probably add similar code to other OSes. Also silence rio warning from earlier commit.

Using plain 'clang' does not work well for the new devdraw on macOS 10.14. But 'xcrun --sdk macosx clang' does work, for reasons no one understands. Hopefully this will be OK on all macOS systems.

X11 headers detection, so that enable fontsrv build on OpenBSD. Change-Id: I2f3f766339a9f8beed647dfbb19a588d1825732a Reviewed-on: https://plan9port-review.googlesource.com/1290 Reviewed-by: Russ Cox <rsc@google.com>

Thanks to Akshat Kumar for reporting this issue. LGTM=seed, rsc R=rsc, seed https://codereview.appspot.com/173770043

They'll be copied back during installation but then hg doesn't have to create those files on systems that have trouble with them. TBR=rsc https://codereview.appspot.com/105800043

And uses gcc for i386 and x86_64. LGTM=rsc R=rsc https://codereview.appspot.com/69860044

Fix compilation problems, libdraw still doesn't work right yet. LGTM=rsc R=rsc https://codereview.appspot.com/67820046