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/time.h

@@ -35,8 +35,7 @@ extern "C" {
 #define __tm_zone tm_zone
 #endif
 
-struct tm
-{
+struct tm {
 	int tm_sec;
 	int tm_min;
 	int tm_hour;
@@ -78,8 +77,7 @@ char *ctime_r (const time_t *, char *);
 
 void tzset (void);
 
-struct itimerspec
-{
+struct itimerspec {
 	struct timespec it_interval;
 	struct timespec it_value;
 };