This fixes a lintian warning.

This is needed for older compilers (like Wheezy's gcc 4.7.2 and Jessie's
gcc 4.9.2) to accept "modern" things like for-loops with the index
variable declared in them:

hostmot2.c:759:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for (int i = 0; i < num_pins; i ++) {
      ^
hostmot2.c:759:5: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code

This also means we no longer need to override CFLAGS in the travis config.

Make sure the requested filename fits in the `bitfile_name` buffer before
copying it.

This squelches a warning from -D_FORTIFY_SOURCE.

Make sure there's room in the destination buffer for the whole source
string, plus the terminating NULL.

Error out early and print a helpful error message if they're not found.

This makes the `if` statement bodies indent by 4 spaces instead of
sometimes one tab and sometimes nothing.

changes from jethornton/mesaflash master branch

fix a couple of compile warnings