Added ISO-C99 compatible logging
Added ISO-C99 compatible logging

tpm2-tss is supposed to be ISO-C99 compatible. So far, util/log.c
used the function strncasecmp, which is part of the POSIX- and
BSD-standard but not of the ISO-C99-standard.

Therefore, a new function, case_insensitiveItrncmp is introduced. It
creates lowercase-variants of the strings to compare and calls
the C99-compatible standard function strncmp on them. This
mimicks the behavior of strncasecmp but remains compatible with
C99.

* Introduced case_insensitive_trncmp
* Replaced all calls of strncasecompare with it
* Added a Doxygen-style description of the functionality and reason
  of existence of the function caseInsensitiveStrncmp

Signed-off-by: Lukas Jäger <79f73ee2d12cdbbd43079ed4c5384670532b7e18@sit.fraunhofer.de>

tpm2-software/tpm2-tss,01org/tpm2-tss,01org/TPM2.0-TSS,01org/TPM2.0-TSS,01org/TPM2.0-TSS,tpm2-software/tpm2-tss,01org/TPM2.0-TSS,01org/tpm2-tss,tpm2-software/tpm2-tss,01org/tpm2-tss