Commit Briefs
acme: avoid global named "class"
For AIX.
libdiskfs: avoid problematic internal constant names
AIX defines some of these constants in its C header files.
diff: rename class to fix AIX
math.h defines a function named class on AIX.
devdraw: use global drawlk instead of per-client
Setting up for a real window system.
devdraw: use indirect impl interface
Setting up for a real window system.
libthread: add pthreadperthread mode and use under ASAN
ASAN can't deal with the coroutine stacks. In theory we can call into ASAN runtime to let it know about them, but ASAN still has problems with fork or exit happening from a non-system stack. Bypass all possible problems by just having a full OS thread for each libthread thread. The threads are still cooperatively scheduled within a proc (in thos mode, a group of OS threads). Setting the environment variable LIBTHREAD=pthreadperthread will enable the pthreadperthread mode, as will building with CC9FLAGS='-fsanitize=address' in $PLAN9/config. This solution is much more general than ASAN - for example if you are trying to find all the thread stacks in a reproducible crash you can use pthreadperthread mode with any debugger that knows only about OS threads.
INSTALL: build mk all the time
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.
9c, 9l: accept CC9FLAGS from config
Also, if CC9FLAGS includes -fsanitize=address (ASAN), predefine PLAN9PORT_ASAN for use by programs that need to know (mainly libthread). The 9c script used to have a variable called ngflags, which was ccflags except -g (ng stood for "no g"), but nothing needs it split out anymore, so simplify to just ccflags.