nrf/mpconfigport: Enable MICROPY_NLR_THUMB_USE_LONG_JUMP on nRF51xx.

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

ports/nrf/mpconfigport.h

@@ -59,6 +59,12 @@
 
 // options to control how MicroPython is built
 
+// Due to the use of LTO and the unknown distance between nlr.o and nlrthumb.o code,
+// MCUs using the Thumb 1 instruction set must enable this NLR long jump feature.
+#if defined(NRF51822)
+#define MICROPY_NLR_THUMB_USE_LONG_JUMP    (1)
+#endif
+
 #ifndef MICROPY_VFS
 #define MICROPY_VFS                        (CORE_FEAT)
 #endif