Add -mno-relax to CFLAGS in bsd.prog/lib.mk instead of bsd.cpu.mk.

bsd.cpu.mk is included by bsd.init.mk before bsd.linker.mk, so it
was always setting the flag since LINKER_FEATURES wasn't defined.

Reported by:	mhorne
Reviewed by:	imp, mhorne
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D23076

share/mk/bsd.cpu.mk

@@ -375,10 +375,6 @@ CFLAGS += -march=rv64imac -mabi=lp64
 .else
 CFLAGS += -march=rv64imafdc -mabi=lp64d
 .endif
-
-.if ${LINKER_FEATURES:U:Mriscv-relaxations} == ""
-CFLAGS += -mno-relax
-.endif
 .endif
 
 # NB: COPTFLAGS is handled in /usr/src/sys/conf/kern.pre.mk

share/mk/bsd.lib.mk

@@ -98,6 +98,10 @@ STATIC_CFLAGS+= -ftls-model=initial-exec
 STATIC_CXXFLAGS+= -ftls-model=initial-exec
 .endif
 
+.if ${MACHINE_CPUARCH} == "riscv" && ${LINKER_FEATURES:Mriscv-relaxations} == ""
+CFLAGS += -mno-relax
+.endif
+
 .include <bsd.libnames.mk>
 
 # prefer .s to a .c, add .po, remove stuff not used in the BSD libraries

share/mk/bsd.prog.mk

@@ -57,6 +57,10 @@ LDFLAGS+= -Wl,-zretpolineplt
 .endif
 .endif
 
+.if ${MACHINE_CPUARCH} == "riscv" && ${LINKER_FEATURES:Mriscv-relaxations} == ""
+CFLAGS += -mno-relax
+.endif
+
 .if defined(CRUNCH_CFLAGS)
 CFLAGS+=${CRUNCH_CFLAGS}
 .else