I touched symtab.h and was surprised to see how many files were
rebuilt. I looked into it a bit, and found that defs.h includes
gdbarch.h, which in turn includes many things.
gdbarch.h is only needed by a minority ofthe files in gdb, so this
patch removes the include from defs.h and updates the fallout.
I did "wc -l" on the files in build/gdb/.deps; this patch reduces the
line count from 139935 to 137030; so there are definitely future
build-time savings here.
Note that while I configured with --enable-targets=all, it's possible
that some *-nat.c file needs an update. I could not test all of
these. The buildbot caught a few problems along these lines.
gdb/ChangeLog
2019-07-10 Tom Tromey <tom@tromey.com>