libsemanage: respect shell paths with /usr prefix #614

Job	Run time
build (gcc, 3.12, 3.3)	1m 30s
build (gcc, 3.12, 3.3, test-flags-override)	1m 23s
build (gcc, 3.12, 3.3, test-debug)	1m 26s
build (gcc, 3.12, 3.3, linker-bfd)	1m 28s
build (gcc, 3.12, 3.3, linker-gold)	1m 32s
build (gcc, 3.11, 3.3)	1m 33s
build (gcc, 3.10, 3.3)	1m 29s
build (gcc, 3.9, 3.3)	1m 39s
build (gcc, 3.8, 3.3)	2m 38s
build (gcc, 3.7, 3.3)	1m 42s
build (gcc, pypy3.7, 3.3)	1m 55s
build (gcc, 3.12, 3.2)	1m 32s
build (gcc, 3.12, 3.1)	1m 45s
build (gcc, 3.12, 3.0)	1m 30s
build (gcc, 3.12, 2.7)	1m 44s
build (gcc, 3.12, 2.6)	1m 46s
build (gcc, 3.12, 2.5)	1m 44s
build (clang, 3.12, 3.3)	1m 44s
build (clang, 3.12, 3.3, test-flags-override)	1m 31s
build (clang, 3.12, 3.3, test-debug)	1m 41s
build (clang, 3.11, 3.3)	1m 38s
build (clang, 3.10, 3.3)	1m 43s
build (clang, 3.9, 3.3)	1m 43s
build (clang, 3.8, 3.3)	1m 38s
build (clang, 3.7, 3.3)	1m 49s
build (clang, pypy3.7, 3.3)	2m 0s
build (clang, 3.12, 3.2)	1m 38s
build (clang, 3.12, 3.1)	1m 44s
build (clang, 3.12, 3.0)	1m 44s
build (clang, 3.12, 2.7)	1m 52s
build (clang, 3.12, 2.6)	1m 57s
build (clang, 3.12, 2.5)	2m 2s
build (gcc, 3.12, 3.3, sanitizers)	2m 3s
	56m 43s

Provide feedback