FcConfigSubstituteWithPat - Execute substitutions
#include <fontconfig/fontconfig.h>
FcBool FcConfigSubstituteWithPat (FcConfig *config, FcPattern *p, FcPattern *p_pat, FcMatchKind kind);
Performs the sequence of pattern modification operations, if kind is
FcMatchPattern, then those tagged as pattern operations are applied, else if
kind is FcMatchFont, those tagged as font operations are applied and
p_pat is used for <test> elements with target=pattern. Returns FcFalse
if the substitution cannot be performed (due to allocation failure). Otherwise
returns FcTrue. If config is NULL, the current configuration is used.