Revert "Fix strcpy.c that should have been strcpy.S. DO NOT MERGE"

This reverts commit e938349d732a30b356eb6f9334e6c34e213cca56.
Revert "Optimize strcat/strcpy, small tweaks to strlen. DO NOT MERGE"

This reverts commit 13bb94108cd2cb42f7d9a872e0719f87bb240f8c.