misc/rumprun: Add missing USES=gmake and fix build

make[1]: "/wrkdirs/usr/ports/misc/rumprun/work/rumprun-8fe40c8/app-tools/Makefile" line 1: Missing dependency operator
make[1]: "/wrkdirs/usr/ports/misc/rumprun/work/rumprun-8fe40c8/app-tools/Makefile" line 2: Need an operator
...
make[1]: "../../global.mk" line 1: Missing dependency operator
make[1]: "../../global.mk" line 2: Need an operator
...
Variable MACHINE_GNU_PLATFORM is recursive.

• Patch bundled libunwind to build with newer GCC versions
• Fix man page install location
• Fix build on i386
• The port will only build on amd64 and i386 so use ONLY_FOR_ARCHS to list the architectures it builds on instead of all architectures it doesn't build on

PR: 225152
Submitted by: Fabian Freyer <fabian.freyer@physik.tu-berlin.de> (maintainer)