Fix: multiple MbedTLS integration fixes

List of changes:
- prefetched source is ignored by MbedTLS.cmake
  Setting MBEDTLS_SOURCE_DIR does not make MbedTLS.cmake to use the
  externally provided source code. This is because MBEDTLS_SOURCE_DIR
  is not passed to LazyFetch_MakeAvailable().
  As a fix, pass the variable to LazyFetch.
- patch MbedTLS to allow building libmbedcrypto only. This is needed to
  decrease dependencies in yocto.
- allow passing python interpreter location down to MbedTLS build

Change-Id: I25b598e086f5f2af948cd288c2f3faa50bce1cc6
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>
3 files changed