Extract common spiflash.c into core. Use spiflash.c in sysparam. Use memcpy in spiflash.c insted of hand-written version. Tests for spiflash.c
Replacements for: libmain/misc.o libmain/os_cpu_a.o libmain/spi_flash.o libmain/timers.o libmain/uart.o libmain/xtensa_context.o