* builds/unix/configure.raw: Check for 'librsvg'.
(LIB_CLOCK_GETTIME): Don't call `AC_SUBST` on this but on...
(FT_DEMO_CFLAGS, FT_DEMO_LDFLAGS): ... these two new variables.
* builds/unix/unix-cc.in (LIB_CLOCK_GETTIME): Replaced by...
(FT_DEMO_CFLAGS, FT_DEMO_LDFLAGS): ... these two new variables.