lang/rust-bootstrap: Update sysroot to build the rust bootstrap

• Update the sysroot to 11.4 to build the rust bootstrap on amd64, arm64, armv6 and i386
• Regen the sysroot for armv7 (it only includes the necessary bits: /lib, /usr/include and /usr/lib)
• Update the sysroot for powerpc64-elfv2 (previous one is 9 months old)

The sysroot is just the base.txz fetched from ftp://ftp.freebsd.org/pub/FreeBSD/
It's based on the WANDBOARD image for armv6 and armv7

Differential Revision: D26646