fix emacs tabs mode

fix seg when passing NULL to strstr
use zstr to detect empty str
fix compiler warning about || and &&

CID: 1294434 fixing a sizeof statement that was working for so long because on 64bit boxes the pointer size would be 64bits and the uint8_t was expecting at least 32

change configure detection to do FHS layout if you specify a prefix, unless --disable-fhs is passed to configure
moved includes to be under /usr/include/freeswitch dir in fhs layout
install font files into fonts_dir

when the encoder returns 0, it means no more data will come and we should not try again

FS-7519: increase default video buffer to 2mb in avformat and add vbuf file param to change it per file using a number of bytes with k or m modifier for kilobytes and megabytes