tracing/runtime: Teach g_typedef to extract type definition for non-struct types

With previous sed expression it was failing e.g. on runtime.guintptr,
giving much more after type definition:

	$ go doc -c -u runtime.muintptr | sed -n -e '/^type /,/^}/p'
	type muintptr uintptr
	    muintptr is a *m that is not tracked by the garbage collector.

	    Because we do free Ms, there are some additional constrains on muintptrs:

	    1. Never hold an muintptr locally across a safe point.

	    2. Any muintptr in the heap must be owned by the M itself so it can

	    ensure it is not in use when the last true *m is released.

	func (mp muintptr) ptr() *m
	func (mp *muintptr) set(m *m)

Fix it since we'll need to extract more single-line types for Go1.11 support.

To verify it works de-stub {g,p,m}uintptr.

tracing/internal/xruntime/g_typedef

@@ -18,9 +18,17 @@ goset() {
 
 # typedef <type> - print type definition
 typedef() {
-	$goexec doc -c -u $1 |sed -n -e '/^type /,/^}/p'
-}
+	$goexec doc -c -u $1 |sed -n -e '
+# ignore anything not starting with `type `
+/^type /!b
+
+# if there is opening `{` - loop till closing `}`
+/{/{:loop p; n; /^}/!b loop; p; b}
 
+# else just print this single line
+p
+'
+}
 
 # typedef_g 	- print <g> & friends definitions
 typedef_g() {
@@ -33,7 +41,9 @@ typedef_g() {
 	#typedef runtime.sudog
 	#typedef runtime.hchan
 	typedef runtime.timer
-	#typedef runtime.guintptr
+	typedef runtime.guintptr
+	typedef runtime.puintptr
+	typedef runtime.muintptr
 	#typedef runtime.m
 
 	if (( $govern < 109 )); then
@@ -46,9 +56,6 @@ typedef_g_fixed() {
 	typedef_g $1 | \
 		sed -e 's/\<sys.Uintreg\>/uintreg/'
 
-	echo "type guintptr uintptr	// XXX stub"
-	echo "type puintptr uintptr	// XXX stub"
-	echo "type muintptr uintptr	// XXX stub"
 	echo "type uintreg  uint	// FIXME wrong on amd64p32"
 	echo "type m struct {}		// FIXME stub"
 	echo "type sudog struct {}	// FIXME stub"

tracing/internal/xruntime/zruntime_g_go1.10.go

@@ -124,9 +124,9 @@ type timer struct {
 	arg    interface{}
 	seq    uintptr
 }
-type guintptr uintptr	// XXX stub
-type puintptr uintptr	// XXX stub
-type muintptr uintptr	// XXX stub
+type guintptr uintptr
+type puintptr uintptr
+type muintptr uintptr
 type uintreg  uint	// FIXME wrong on amd64p32
 type m struct {}		// FIXME stub
 type sudog struct {}	// FIXME stub

tracing/internal/xruntime/zruntime_g_go1.8.go

@@ -128,13 +128,13 @@ type timer struct {
 	arg    interface{}
 	seq    uintptr
 }
+type guintptr uintptr
+type puintptr uintptr
+type muintptr uintptr
 type stkbar struct {
 	savedLRPtr uintptr // location overwritten by stack barrier PC
 	savedLRVal uintptr // value overwritten at savedLRPtr
 }
-type guintptr uintptr	// XXX stub
-type puintptr uintptr	// XXX stub
-type muintptr uintptr	// XXX stub
 type uintreg  uint	// FIXME wrong on amd64p32
 type m struct {}		// FIXME stub
 type sudog struct {}	// FIXME stub

tracing/internal/xruntime/zruntime_g_go1.9.go

@@ -120,9 +120,9 @@ type timer struct {
 	arg    interface{}
 	seq    uintptr
 }
-type guintptr uintptr	// XXX stub
-type puintptr uintptr	// XXX stub
-type muintptr uintptr	// XXX stub
+type guintptr uintptr
+type puintptr uintptr
+type muintptr uintptr
 type uintreg  uint	// FIXME wrong on amd64p32
 type m struct {}		// FIXME stub
 type sudog struct {}	// FIXME stub