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.

arch/mips/bits/msg.h

@@ -1,5 +1,4 @@
-struct msqid_ds
-{
+struct msqid_ds {
 	struct ipc_perm msg_perm;
 #if _MIPSEL || __MIPSEL || __MIPSEL__
 	time_t msg_stime;

arch/mips/bits/shm.h

@@ -1,7 +1,6 @@
 #define SHMLBA 4096
 
-struct shmid_ds
-{
+struct shmid_ds {
 	struct ipc_perm shm_perm;
 	size_t shm_segsz;
 	time_t shm_atime;

arch/mips/bits/signal.h

@@ -17,8 +17,7 @@ typedef struct {
 		} fp_fregs[32];
 	} fp_r;
 } fpregset_t;
-struct sigcontext
-{
+struct sigcontext {
 	unsigned sc_regmask, sc_status;
 	unsigned long long sc_pc, sc_regs[32], sc_fpregs[32];
 	unsigned sc_ownedfp, sc_fpc_csr, sc_fpc_eir, sc_used_math, sc_dsp;

arch/mips/bits/socket.h

@@ -1,5 +1,4 @@
-struct msghdr
-{
+struct msghdr {
 	void *msg_name;
 	socklen_t msg_namelen;
 	struct iovec *msg_iov;
@@ -9,8 +8,7 @@ struct msghdr
 	int msg_flags;
 };
 
-struct cmsghdr
-{
+struct cmsghdr {
 	socklen_t cmsg_len;
 	int cmsg_level;
 	int cmsg_type;

arch/mips/bits/stat.h

@@ -1,8 +1,7 @@
 /* copied from kernel definition, but with padding replaced
  * by the corresponding correctly-sized userspace types. */
 
-struct stat
-{
+struct stat {
 	dev_t st_dev;
 	long __st_padding1[2];
 	ino_t st_ino;