Try -fweb -frename-registers to make more SAMD21 builds fit

Author: dhalbert

ports/atmel-samd/mpconfigport.mk

@@ -78,10 +78,8 @@ SUPEROPT_VM = 0
 
 CIRCUITPY_LTO_PARTITION = one
 
-ifeq ($(CIRCUITPY_FULL_BUILD),0)
-# On the smallest boards, this saves about 180 bytes. On other boards, it may -increase- space used.
+# On smaller builds this saves about 180 bytes. On other boards, it may -increase- space used, so use with care.
 CFLAGS_BOARD = -fweb -frename-registers
-endif
 
 endif # samd21
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