build: separate compiler and libs

compiler/internal/runtime/goarch/endian_big.go

@@ -0,0 +1,7 @@
+//go:build 386 || amd64 || arm || arm64 || ppc64le || mips64le || mipsle || riscv64 || wasm
+// +build 386 amd64 arm arm64 ppc64le mips64le mipsle riscv64 wasm
+
+package goarch
+
+const BigEndian = true
+const LittleEndian = false

compiler/internal/runtime/goarch/endian_little.go

@@ -0,0 +1,9 @@
+//go:build ppc64 || s390x || mips || mips64
+// +build ppc64 s390x mips mips64
+
+package goarch
+
+const (
+	BigEndian    = false
+	LittleEndian = true
+)

compiler/internal/runtime/goarch/goarch.go

@@ -0,0 +1,3 @@
+package goarch
+
+const PtrSize = 4 << (^uintptr(0) >> 63)