Fix: Stop opteesp environment using default libc

The opteesp environment uses the libc implementation part of the
SPDEV-KIT. Projects targeting the opteesp environment shall be
configured to stop using the standard library and its header files
part of the compiler package.
This patch:
  - adds the missing compiler and linker options
  - adds header files missing from SPDEV-KITs libc implementation
  - extends the external component cmake files to align build options
    with the main project
  - moves environment specific mandatory flags to a common file
  - fixes the supported C standard from gnuc99 to c99

The following files where forked from TF-A
 (https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git; SHA: 7737fdf0ed):
- stdarg.h
- stdbool.h
- stddef.h
- stddef_.h

Signed-off-by: Andrew Beggs <andrew.beggs@arm.com>
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>
Change-Id: I3890453a29b003c60c8f44dfd19d553e96b1796c
diff --git a/deployments/env-test/env_test.cmake b/deployments/env-test/env_test.cmake
index 9c0926b..ee46eba 100644
--- a/deployments/env-test/env_test.cmake
+++ b/deployments/env-test/env_test.cmake
@@ -44,5 +44,8 @@
 #-------------------------------------------------------------------------------
 
 # Mbed TLS provides libmbedcrypto
+list(APPEND MBEDTLS_EXTRA_INCLUDES ${SP_DEV_KIT_INCLUDE_DIR})
+set(MBEDTLS_EXTRA_INCLUDES ${MBEDTLS_EXTRA_INCLUDES}
+	CACHE STRING "PSA ITS for Mbed TLS" FORCE)
 include(${TS_ROOT}/external/MbedTLS/MbedTLS.cmake)
 target_link_libraries(env-test PRIVATE mbedcrypto)