runtime: rename gothrow to throw

Rename "gothrow" to "throw" now that the C version of "throw"
is no longer needed.

This change is purely mechanical except in panic.go where the
old version of "throw" has been deleted.

sed -i "" 's/[[:<:]]gothrow[[:>:]]/throw/g' runtime/*.go

Change-Id: Icf0752299c35958b92870a97111c67bcd9159dc3
Reviewed-on: https://go-review.googlesource.com/2150
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
diff --git a/src/runtime/iface.go b/src/runtime/iface.go
index 6be1df7..f62e51a 100644
--- a/src/runtime/iface.go
+++ b/src/runtime/iface.go
@@ -26,7 +26,7 @@
 
 func getitab(inter *interfacetype, typ *_type, canfail bool) *itab {
 	if len(inter.mhdr) == 0 {
-		gothrow("internal error - misuse of itab")
+		throw("internal error - misuse of itab")
 	}
 
 	// easy case
@@ -114,7 +114,7 @@
 	nextimethod:
 	}
 	if locked == 0 {
-		gothrow("invalid itab locking")
+		throw("invalid itab locking")
 	}
 	m.link = hash[h]
 	atomicstorep(unsafe.Pointer(&hash[h]), unsafe.Pointer(m))