Fix build of compiler-rt on FreeBSD

Broken since ee6011f removed cmake from the
process.  There are likely other platforms still broken, but I didn't test on
them.

Author: asomers

mk/rt.mk

@@ -384,7 +384,11 @@ COMPRT_OBJS_$(1) += emutls.o
 endif
 
 ifeq ($$(findstring msvc,$(1)),)
+
+ifeq ($$(findstring freebsd,$(1)),)
 COMPRT_OBJS_$(1) += gcc_personality_v0.o
+endif
+
 COMPRT_OBJS_$(1) += emutls.o
 
 ifeq ($$(findstring x86_64,$(1)),x86_64)