esp32: remove dead code and fix GC root scanning

Remove unused cpuIntUsed and cpuIntToPeripheral variables from
interrupt_esp32.go because these were declared but never read.

Fix _globals_end in the linker script to cover .data in addition to
.bss and .wifi_bss. Previously the GC scan range ended at
_wifi_bss_end, missing any heap pointers stored in initialized
globals (.data section). Extend to _edata so the conservative
collector sees all global root pointers.

Signed-off-by: deadprogram <ron@hybridgroup.com>

src/runtime/interrupt/interrupt_esp32.go

@@ -53,13 +53,6 @@ const (
 	lastCPUInt  = 30
 )
 
-// cpuIntUsed tracks which CPU interrupt lines have been allocated.
-var cpuIntUsed [32]bool
-
-// cpuIntToPeripheral maps CPU interrupt number → peripheral IRQ source,
-// so that handleInterrupt can dispatch to the correct Go handler.
-var cpuIntToPeripheral [32]int
-
 // inInterrupt is set while we're inside the interrupt handler so that
 // interrupt.In() returns the correct value.
 var inInterrupt bool
@@ -75,9 +68,6 @@ func (i Interrupt) Enable() error {
 		return errInterruptRange
 	}
 
-	// Mark as used.
-	cpuIntUsed[i.num] = true
-
 	// Read current INTENABLE, set the bit for this CPU interrupt.
 	cur := readINTENABLE()
 	cur |= 1 << uint(i.num)

targets/esp32.ld

@@ -185,7 +185,7 @@ SECTIONS
 
 /* For the garbage collector. */
 _globals_start = _sbss;
-_globals_end = _wifi_bss_end;
+_globals_end = _edata;
 _heap_start = _edata;
 /* Go GC heap = the rest of SRAM2 above .data (~113KB), a single safe contiguous
  * block. The WiFi arena lives in DRAM1 (SRAM1 pool 7/6), so its ~64KB does not