Minimize L32R use with new compiler optimization

See earlephilhower/esp-quick-toolchain#36 (comment)

Author: earlephilhower

conf/esp8266.mk

@@ -10,7 +10,7 @@ BUILD = esp8266
 # C compiler, linker, and static library builder.
 TOOLCHAIN_PREFIX := xtensa-lx106-elf-
 CC := $(TOOLCHAIN_PREFIX)gcc
-CFLAGS = -W -Wall -g -O2 -Wpointer-arith -Wl,-EL -nostdlib -mlongcalls -mno-text-section-literals -ffunction-sections -fdata-sections -Werror -free -fipa-pta
+CFLAGS = -W -Wall -g -O2 -Wpointer-arith -Wl,-EL -nostdlib -mlongcalls -mno-text-section-literals -ffunction-sections -fdata-sections -Werror -free -fipa-pta -mextra-l32r-costs=5
 CFLAGS += -D__ets__ -DICACHE_FLASH -DESP8266 -DBR_SLOW_MUL15=1 -DPGM_READ_UNALIGNED=0
 LD := $(TOOLCHAIN_PREFIX)ld
 AR := $(TOOLCHAIN_PREFIX)ar