teensy: Provide own implementation of gc_collect, to not use stm32.

Signed-off-by: Damien George <damien@micropython.org>

ports/teensy/Makefile

@@ -95,7 +95,6 @@ SRC_C = \
 	usb.c \
 
 STM_SRC_C = $(addprefix ports/stm32/,\
-	gccollect.c \
 	irq.c \
 	pin.c \
 	pin_named_pins.c \

ports/teensy/main.c

@@ -9,6 +9,7 @@
 #include "py/gc.h"
 #include "py/mphal.h"
 #include "gccollect.h"
+#include "lib/utils/gchelper.h"
 #include "lib/utils/pyexec.h"
 #include "lib/mp-readline/readline.h"
 #include "lexermemzip.h"
@@ -349,6 +350,12 @@ soft_reset:
     goto soft_reset;
 }
 
+void gc_collect(void) {
+    gc_collect_start();
+    gc_helper_collect_regs_and_stack();
+    gc_collect_end();
+}
+
 // stub out __libc_init_array. It's called by mk20dx128.c and is used to call
 // global C++ constructors. Since this is a C-only projects, we don't need to
 // call constructors.