imagebld: Fix parameters in printf calls

[binarymaster]

Fixes #8.

[JayFoxRox]

Amazingly, the old code still worked fine for me, because the argument remains on stack (in register?) with my default compiler setup. Not even valgrind will complain.

Anyhow, new version should be more stable.

For the future, we should consider adding -Wall; which also warns about another case which might cause imagebld to misbehave:

lib/imagebld/imagebld.c:148:28: warning: argument to ‘sizeof’ in ‘memset’ call is the same expression as the destination; did you mean to provide an explicit length? [-Wsizeof-pointer-memaccess]
  148 |      memset(xbe,0x00,sizeof(xbe));
      |                            ^