Unbreak riscv build in universe.

riscv doesn't have -msoft-float. For the moment, just don't add
anything. There's no /boot/loader or other bootstrap contained in the
tree for riscv*. However, with real hardware coming next year, there
are plans for one, so keep building at least a minimal libsa and
ficl to prevent bitrot.

Sponsored by: Netflix

stand/Makefile.inc

@@ -10,10 +10,12 @@ CFLAGS+=-I${SASRC}
 SSP_CFLAGS=
 
 # Add in the no float / no SIMD stuff and announce we're freestanding
+# aarch64 and riscv don't have -msoft-float, but all others do. riscv
+# currently has no /boot/loader, but may soon.
 CFLAGS+=	-ffreestanding ${CFLAGS_NO_SIMD}
 .if ${MACHINE_CPUARCH} == "aarch64"
 CFLAGS+=	-mgeneral-regs-only
-.else
+.elif ${MACHINE_CPUARCH} != "riscv"
 CFLAGS+=	-msoft-float
 .endif