Aligned with termux_step_post_get_source in build.sh.

--- a/configure.ac
+++ b/configure.ac
@@ -376,8 +376,8 @@
 AM_CONDITIONAL(FLaC__HAS_DOXYGEN, test -n "$DOXYGEN")
 
 if test  "x$DOXYGEN" = "x"; then
-	AC_CHECK_FILE($srcdir/doc/FLAC.tag,[HAVE_PREBUILT_FLAC_TAG=yes])
-	AC_CHECK_FILE($srcdir/doc/api/modules.html,[HAVE_PREBUILT_API_DIR=yes])
+	HAVE_PREBUILT_FLAC_TAG=yes
+	HAVE_PREBUILT_API_DIR=yes
 fi
 AM_CONDITIONAL(FLaC__HAS_PREBUILT_DOXYGEN, test "x$HAVE_PREBUILD_FLAG_TAG$HAVEPREBUILD_API_DIR" = "xyesyes")