Remove unused flags.Nocrt

Nocrt is handled through deps.CrtBegin/End, flags.Nocrt is unused

Change-Id: I8ab5313bb2eb3a00e336504d6dd3813350fbe14d
Test: soong builds

cc/cc.go

@@ -94,7 +94,6 @@ type Flags struct {
 	LdFlags     []string // Flags that apply to linker command lines
 	libFlags    []string // Flags to add libraries early to the link order
 
-	Nocrt     bool
 	Toolchain config.Toolchain
 	Clang     bool