[ltsmaster] Add setjmp/ucontext definitions for FreeBSD/aarch64

[valpackett]

This is dlang#2269 which is still not cherry-picked into ltsmaster

[kinke]

Is this really needed? [ltsmaster just needs to be able to compile the current/a recent version of LDC]

[valpackett]

Yes, it can't compile its own runtime with these types missing.

cd /usr/ports/lang/ldc/work/ldc-1.15.0/ltsmaster && /usr/ports/lang/ldc/work/ldc-1.15.0/ltsmaster/bin/ldc2 --output-o -c -I/usr/ports/lang/ldc/work/ldc-1.15.0/ltsmaster/runtime/druntime/src -I/usr/ports/lang/ldc/work/ldc-1.15.0/ltsmaster/runtime/druntime/src/gc /usr/ports/lang/ldc/work/ldc-1.15.0/ltsmaster/runtime/druntime/src/core/sys/posix/setjmp.d -of=/usr/ports/lang/ldc/work/ldc-1.15.0/ltsmaster/runtime/src/core/sys/posix/setjmp-debug.o -w -g -link-debuglib -disable-invariants
/usr/ports/lang/ldc/work/ldc-1.15.0/ltsmaster/runtime/druntime/src/core/sys/posix/setjmp.d(168): Error: undefined identifier '_jmp_buf', did you mean alias 'jmp_buf'?
/usr/ports/lang/ldc/work/ldc-1.15.0/ltsmaster/runtime/druntime/src/core/sys/posix/setjmp.d(255): Error: undefined identifier '_sigjmp_buf', did you mean alias 'sigjmp_buf'?

[kinke]

Alright, thx. Is this the last (edit: ltsmaster) blocker for FreeBSD/aarch64?

[valpackett]

well, this and

--- ltsmaster/runtime/phobos/std/internal/math/gammafunction.d.orig     2019-04-20 23:21:36 UTC
+++ ltsmaster/runtime/phobos/std/internal/math/gammafunction.d
@@ -1654,7 +1654,6 @@ real logmdigammaInverse(real y)
 {
     import std.numeric: findRoot;
     enum maxY = logmdigamma(real.min_normal);
-    static assert(maxY > 0 && maxY <= real.max);

     if (y >= maxY)
     {