wrap-for-bin.sh: regenerate bin-wrappers when switching branches

Commit e6e7530 (test helpers: move test-* to t/helper/ subdirectory - 2016-04-13) moves test-* to t/helper. However because bin-wrappers/* only depend on wrap-for-bin.sh, when switching between a branch that has this commit and one that does not, bin-wrappers/* may not be regenerated and point to the old/outdated test programs. This commit makes a non-functional change in wrap-for-bin.sh, just enough for 'make' to detect and re-execute wrap-for-bin.sh. When switching between a branch containing both this commit and e6e7530 and one containing neither, bin-wrappers/*, we should get fresh bin-wrappers/*. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>