Merge branch 'jk/portable'

* jk/portable: t6000lib: re-fix tr portability t7505: use SHELL_PATH in hook t9112: add missing #!/bin/sh header filter-branch: use $SHELL_PATH instead of 'sh' filter-branch: don't use xargs -0 add NO_EXTERNAL_GREP build option t6000lib: tr portability fix t4020: don't use grep -a add test_cmp function for test scripts remove use of "tail -n 1" and "tail -1" grep portability fix: don't use "-e" or "-q" more tr portability test script fixes t0050: perl portability fix tr portability fixes