x/sys/unix: regenerate darwin/amd64 outputs with the latest SDK

I did this on OS X 10.10.5 (14F27) using the 10.10 SDK included in Xcode
6.4 (6E35b). This required removing a C include from mkerrors.sh, since
it doesn't exist on either of my two systems.

I spot checked the syscall number changes against this definitive list,
which is for approximately my kernel version:

    http://www.opensource.apple.com/source/xnu/xnu-2782.20.48/bsd/kern/syscalls.master

Everything I examined checked out, including the removed syscalls being
marked as "old" or being described in comments as no longer existing.

There is one exception to the output being cleanly autogenerated: I have
manually renamed SYS_SYSCTL back to SYS___SYSCTL, the name used
previously and still used by syscall_bsd.go. Because it would distract
from this CL, I will fix this in an upcoming CL.

Change-Id: I0168f608cab714aa5981b3e7d08d8fd84888d0d5
Reviewed-on: https://go-review.googlesource.com/14006
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/mkall.sh

@@ -121,7 +121,7 @@ darwin_386)
 	;;
 darwin_amd64)
 	mkerrors="$mkerrors -m64"
-	mksysnum="./mksysnum_darwin.pl /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/sys/syscall.h"
+	mksysnum="./mksysnum_darwin.pl /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk/usr/include/sys/syscall.h"
 	mktypes="GOARCH=$GOARCH go tool cgo -godefs"
 	;;
 darwin_arm)
@@ -267,5 +267,8 @@ esac
 	esac
 	if [ -n "$mksysctl" ]; then echo "$mksysctl |gofmt >$zsysctl"; fi
 	if [ -n "$mksysnum" ]; then echo "$mksysnum |gofmt >zsysnum_$GOOSARCH.go"; fi
-	if [ -n "$mktypes" ]; then echo "$mktypes types_$GOOS.go | gofmt >ztypes_$GOOSARCH.go"; fi
+	if [ -n "$mktypes" ]; then
+		echo "echo // +build $GOARCH,$GOOS > ztypes_$GOOSARCH.go";
+		echo "$mktypes types_$GOOS.go | gofmt >>ztypes_$GOOSARCH.go";
+	fi
 ) | $run