siginfo.h: add a missing function member on ia64, mips and sparc arches

Add "__pid_t _tid" member which is used for some packages, like rt-test
for instance, which fails with an error like this one:

src/cyclictest/cyclictest.c:638:9: error: 'union <anonymous>' has no
member named '_tid'

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

libc/sysdeps/linux/ia64/bits/siginfo.h

@@ -309,6 +309,10 @@ typedef struct sigevent
       {
 	int _pad[__SIGEV_PAD_SIZE];
 
+	/* When SIGEV_SIGNAL and SIGEV_THREAD_ID set, LWP ID of the
+	   thread to receive the signal.  */
+	__pid_t _tid;
+
 	struct
 	  {
 	    void (*_function) (sigval_t);	/* Function to start.  */

libc/sysdeps/linux/mips/bits/siginfo.h

@@ -281,6 +281,10 @@ typedef struct sigevent
       {
 	int _pad[__SIGEV_PAD_SIZE];
 
+	/* When SIGEV_SIGNAL and SIGEV_THREAD_ID set, LWP ID of the
+	   thread to receive the signal.  */
+	__pid_t _tid;
+
 	struct
 	  {
 	    void (*_function) (sigval_t);	/* Function to start.  */

libc/sysdeps/linux/sparc/bits/siginfo.h

@@ -288,6 +288,10 @@ typedef struct sigevent
       {
 	int _pad[__SIGEV_PAD_SIZE];
 
+	/* When SIGEV_SIGNAL and SIGEV_THREAD_ID set, LWP ID of the
+	   thread to receive the signal.  */
+	__pid_t _tid;
+
 	struct
 	  {
 	    void (*_function) (sigval_t);	/* Function to start.  */