syscall: fix mksysnum_linux.sh

A few system call numbers on x86 Linux are
defined in terms of a previous definition,

e.g.,
	#define __NR_timer_create	259
	#define __NR_timer_settime	(__NR_timer_create+1)
	...
	#define __NR_mq_open		277
	#define __NR_mq_unlink		(__NR_mq_open+1)

This change assumes the numbers are sorted
sequentially in the input file.

R=rsc, bradfitzwork
CC=golang-dev
https://golang.org/cl/3946041

src/pkg/syscall/mksysnum_linux.sh

@@ -14,12 +14,20 @@ package syscall
 const(
 EOF
 
+sub fmt {
+	my ($name, $num) = @_;
+	$name =~ y/a-z/A-Z/;
+	print "	SYS_$name = $num;\n";
+}
+
+my $prev;
 while(<>){
 	if(/^#define __NR_(\w+)\s+([0-9]+)/){
-		my $name = "SYS_$1";
-		my $num = $2;
-		$name =~ y/a-z/A-Z/;
-		print "	$name = $num;\n";
+		$prev = $2;
+		fmt($1, $2);
+	}
+	elsif(/^#define __NR_(\w+)\s+\(\w+\+([0-9]+)\)/){
+		fmt($1, $prev+$2)
 	}
 }
 

src/pkg/syscall/zsysnum_linux_386.go

@@ -262,6 +262,14 @@ const (
 	SYS_REMAP_FILE_PAGES       = 257
 	SYS_SET_TID_ADDRESS        = 258
 	SYS_TIMER_CREATE           = 259
+	SYS_TIMER_SETTIME          = 260
+	SYS_TIMER_GETTIME          = 261
+	SYS_TIMER_GETOVERRUN       = 262
+	SYS_TIMER_DELETE           = 263
+	SYS_CLOCK_SETTIME          = 264
+	SYS_CLOCK_GETTIME          = 265
+	SYS_CLOCK_GETRES           = 266
+	SYS_CLOCK_NANOSLEEP        = 267
 	SYS_STATFS64               = 268
 	SYS_FSTATFS64              = 269
 	SYS_TGKILL                 = 270
@@ -272,6 +280,11 @@ const (
 	SYS_GET_MEMPOLICY          = 275
 	SYS_SET_MEMPOLICY          = 276
 	SYS_MQ_OPEN                = 277
+	SYS_MQ_UNLINK              = 278
+	SYS_MQ_TIMEDSEND           = 279
+	SYS_MQ_TIMEDRECEIVE        = 280
+	SYS_MQ_NOTIFY              = 281
+	SYS_MQ_GETSETATTR          = 282
 	SYS_KEXEC_LOAD             = 283
 	SYS_WAITID                 = 284
 	SYS_ADD_KEY                = 286