[PATCH] warnings cleanup

Hi all. I'd like to see osmocom-bb builds less cluttered by compiler warnings - attached is (far from complete) attempt to do so. It's tested which means it builds on my machine and resulting mobile app seems to run fine - no in-depth testing were made. However I'd like to get some feedback before going further: there seems to be some evil hackery happening around src/target/firmware/apps/loader/main.c: Why do we have external "unsigned char _start" which later used as msgb_put_u32(msg, &_start); Do we make some assumptions on the size of unsigned char? Is this documented somewhere by any chance? Also there are plenty of warnings regarding alignment: some things are marked as "__attribute__ ((packed))" and some are not which seems to make compiler unhappy. Is there rule of thumb to decide when we should care about alignment? -- best regards, Max, http://fairwaves.ru