tss2-tcti-mssim/pkg-config: add root dir to CFLAGS
tss2-tcti-mssim/pkg-config: add root dir to CFLAGS

Currently, software building against the various libraries all include
the header files via a suffix directory. However, moving from spec
compliant SAPI implementations should just require a reconfiguration of
the software build parameters, not of the software itself.

Client's could perform their own magic to do this. Some examples I have
seen are to use a macro to define at buildtime where to pull in the
header file. However, since the specifications define the file name, a
include directive of that file name should be sufficient.

For this reason, place the tss2, or suffic directory, on the build
include path returned by pkg-config, so compliant SAPI stacks can be
easily swapped via normal pkg-config semantics. Thus, removing
additional burdens on client applications when switching SAPI's.

Signed-off-by: William Roberts <60148e894dabf0b83bde1d460768794cd453c455@intel.com>

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