make brace placement in public header struct definitions consistent

placing the opening brace on the same line as the struct keyword/tag
is the style I prefer and seems to be the prevailing practice in more
recent additions.

these changes were generated by the command:

find include/ arch/*/bits -name '*.h' \
-exec sed -i '/^struct [^;{]*$/{N;s/\n/ /;}' {} +

and subsequently checked by hand to ensure that the regex did not pick
up any false positives.

include/getopt.h

@@ -9,8 +9,7 @@ int getopt(int, char * const [], const char *);
 extern char *optarg;
 extern int optind, opterr, optopt, optreset;
 
-struct option
-{
+struct option {
 	const char *name;
 	int has_arg;
 	int *flag;