Fix #9: Use /usr/bin/which, not /bin/which, for unit test.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

tests/which.c

@@ -11,13 +11,13 @@ int main(void)
 	int result = 0;
 	size_t i;
 	struct tc test[] = {
-		{ "ls",          1 },
-		{ "free",        1 },
-		{ "modinfo",     1 },
-		{ "useradd",     1 },
-		{ "/bin/which",  1 },
-		{ "/bin/ps aux", 1 },
-		{ "/etc/passwd", 0 },
+		{ "ls",             1 },
+		{ "free",           1 },
+		{ "modinfo",        1 },
+		{ "useradd",        1 },
+		{ "/usr/bin/which", 1 },
+		{ "/bin/ps aux",    1 },
+		{ "/etc/passwd",    0 },
 		{ NULL, 0 }
 	};