* xfns.c (syms_of_xfns): Use make_pure_string instead of build_string.

* xfns.c (syms_of_xfns): Use make_pure_string instead of build_string.
* xterm.c (syms_of_xterm):
* xfaces.c (syms_of_xfaces):
* xdisp.c (syms_of_xdisp):
* lread.c (syms_of_lread):
* keyboard.c (syms_of_keyboard): Use make_pure_c_string instead of
build_string.
* doc.c (Fsnarf_documentation): Purecopy Vbuild_files.