all: make TinyGo code usable with "big Go" CGo

I managed to get CGo sort-of working in VSCode (meaning that it will
typecheck code in the IDE itself) using a few crude hacks, but it
requires a few minor changes to the TinyGo standard library.

I intend to eventually add this support in the TinyGo extension for
VSCode directly, but for now I've manually updated .vscode/settings.json
to get IDE support. In any case, it would be nice to have this for when
I hopefully add this to the TinyGo extension eventually.

src/internal/task/task_stack_arm.S

@@ -1,3 +1,5 @@
+//go:build tinygo
+
 // Only generate .debug_frame, don't generate .eh_frame.
 .cfi_sections .debug_frame
 

src/internal/task/task_stack_avr.S

@@ -1,3 +1,5 @@
+//go:build tinygo
+
 .section .bss.tinygo_systemStack
 .global tinygo_systemStack
 .type   tinygo_systemStack, %object

src/internal/task/task_stack_cortexm.S

@@ -1,3 +1,5 @@
+//go:build tinygo
+
 // Only generate .debug_frame, don't generate .eh_frame.
 .cfi_sections .debug_frame
 

src/internal/task/task_stack_cortexm.go

@@ -52,17 +52,17 @@ func (s *state) archInit(r *calleeSavedRegs, fn uintptr, args unsafe.Pointer) {
 }
 
 func (s *state) resume() {
-	switchToTask(s.sp)
+	tinygo_switchToTask(s.sp)
 }
 
 //export tinygo_switchToTask
-func switchToTask(uintptr)
+func tinygo_switchToTask(uintptr)
 
 //export tinygo_switchToScheduler
-func switchToScheduler(*uintptr)
+func tinygo_switchToScheduler(*uintptr)
 
 func (s *state) pause() {
-	switchToScheduler(&s.sp)
+	tinygo_switchToScheduler(&s.sp)
 }
 
 // SystemStack returns the system stack pointer. On Cortex-M, it is always

src/internal/task/task_stack_esp32.S

@@ -1,3 +1,5 @@
+//go:build tinygo
+
 .section .text.tinygo_startTask,"ax",@progbits
 .global  tinygo_startTask
 .type    tinygo_startTask, %function

src/internal/task/task_stack_esp8266.S

@@ -1,3 +1,5 @@
+//go:build tinygo
+
 .section .text.tinygo_startTask,"ax",@progbits
 .global  tinygo_startTask
 .type    tinygo_startTask, %function

src/internal/task/task_stack_tinygoriscv.S

@@ -1,3 +1,5 @@
+//go:build tinygo
+
 .section .text.tinygo_startTask
 .global  tinygo_startTask
 .type    tinygo_startTask, %function

src/machine/machine_rp2040_rom.go

@@ -1,4 +1,4 @@
-//go:build rp2040
+//go:build tinygo && rp2040
 
 package machine