runtime/cgo: make symbol naming consistent

The naming in this package is a disaster.
Make it all consistent.

Remove some 'static' from functions that will
be referred to from other files soon.

This CL is purely renames using global search and replace.

Submitting separately so that real changes will not
be drowned out by these renames in future CLs.

TBR=iant
CC=golang-dev
https://golang.org/cl/7416046
diff --git a/src/pkg/runtime/asm_amd64.s b/src/pkg/runtime/asm_amd64.s
index 9591437..9879584 100644
--- a/src/pkg/runtime/asm_amd64.s
+++ b/src/pkg/runtime/asm_amd64.s
@@ -14,14 +14,14 @@
 	MOVQ	BX, 24(SP)
 	
 	// create istack out of the given (operating system) stack.
-	// initcgo may update stackguard.
+	// _cgo_init may update stackguard.
 	MOVQ	$runtime·g0(SB), DI
 	LEAQ	(-64*1024+104)(SP), BX
 	MOVQ	BX, g_stackguard(DI)
 	MOVQ	SP, g_stackbase(DI)
 
-	// if there is an initcgo, call it.
-	MOVQ	initcgo(SB), AX
+	// if there is an _cgo_init, call it.
+	MOVQ	_cgo_init(SB), AX
 	TESTQ	AX, AX
 	JZ	needtls
 	// g0 already in DI