add some CFLAGs to shrink binary file size

[MaBecker]

add this CFLAG to get approximately 2.5k less in size (#1207)

-fno-guess-branch-probability -freorder-blocks-and-partition -fno-cse-follow-jumps
without

** user1.bin uses 458324 bytes of 479232 available ESP8266_BOARD
** user1.bin uses 516564 bytes of 962560 available ESP8266_4MB
with

** user1.bin uses 455796 bytes of 479232 available ESP8266_BOARD
** user1.bin uses 513972 bytes of 962560 available ESP8266_4MB