libcasper: fix cap_rights_init usage

Capability rights passed to cap_rights_* are not simple bitmaks and
cannot be ORed together in general (although it will work for certain
subsets of rights).

PR: 277057
Fixes: faaf43b2a750 ("fileargs: add tests")
Sponsored by: The FreeBSD Foundation

lib: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

tests: Skip cap_fileargs if build without capsicum capabilities

Approved by: oshogbo
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D2834

fileargs: add support for realpath

fileargs: add tests