[spice] relocate openssl code into seperate function

This is in preperation of switching to an alternative SSL library
as OpenSSL conflicts with the GNU licence.

client/Makefile

@@ -17,6 +17,7 @@ CFLAGS  += -DBUILD_VERSION='"$(shell git describe --always --long --dirty --abbr
 
 OBJS	= main.o \
 	  lg-renderer.o \
+	  spice/rsa.o \
 	  spice/spice.o \
 	  parsers/nal.o \
 	  decoders/null.o \