xbps-bin(8): added a new target "find-files".

This new target 'find-files' can be used to find which installed
package(s) own a file. Exact matches like "/bin/mount" or patterns
like "/usr/lib/libb[ao]b\*" can be specified.

bin/xbps-bin/main.c

@@ -43,6 +43,7 @@ usage(void)
 	"    autoremove\n"
 	"    autoupdate\n"
 	"    check\t\t[<pkgname>|<all>]\n"
+	"    find-files\t<pattern>\n"
 	"    install\t\t[<pkgname(s)>|<pkgpattern(s)>]\n"
 	"    list\n"
 	"    list-manual\n"
@@ -343,6 +344,16 @@ main(int argc, char **argv)
 
 		rv = xbps_show_pkg_reverse_deps(argv[1]);
 
+	} else if (strcasecmp(argv[0], "find-files") == 0) {
+		/*
+		 * Find files matched by a pattern from installed
+		 * packages.
+		 */
+		if (argc != 2)
+			usage();
+
+		rv = find_files_in_packages(argv[1]);
+
 	} else {
 		usage();
 	}