ext: build libriscv PIC to make it linkable to ext library

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

Makefile.in

@@ -242,7 +242,7 @@ $(2)_lib_libnames_shared	:= $$(if $$($(2)_install_shared_lib),lib$(1).so,)
 
 lib$(1).a : $$($(2)_objs) $$($(2)_c_objs) $$($(2)_lib_libnames)
 	$(AR) rcs $$@ $$^
-lib$(1).so : $$($(2)_objs) $$($(2)_c_objs) $$($(2)_lib_libnames_shared)
+lib$(1).so : $$($(2)_objs) $$($(2)_c_objs) $$($(2)_lib_libnames_shared) $$($(2)_lib_libnames)
 	$(LINK) -shared -o $$@ $(if $(filter Darwin,$(shell uname -s)),-install_name $(install_libs_dir)/$$@) $$^ $$($(2)_lib_libnames) $(LIBS)
 
 $(2)_junk += lib$(1).a

riscv/riscv.mk.in

@@ -7,6 +7,8 @@ riscv_subproject_deps = \
 
 riscv_install_prog_srcs = \
 
+riscv_CFLAGS = -fPIC
+
 riscv_hdrs = \
 	common.h \
 	decode.h \