CMake: greentea: Add skip reason

Add parser to retrieve MBED_RAM_SIZE, MBED_CONF_TARGET_BOOT_STACK_SIZE,
MBED_CONF_RTOS_MAIN_THREAD_STACK_SIZE values from mbed_config.cmake to
calculate available stack which is used for if condition check for skip this test.

hal/tests/TESTS/mbed_hal/stack_size_unification/CMakeLists.txt

@@ -3,9 +3,40 @@
 
 include(mbed_greentea)
 
+if("TARGET_CORTEX_A" IN_LIST MBED_TARGET_DEFINITIONS)
+    set(TEST_SKIPPED "Cortex-A target not supported for this test")
+endif()
+
+macro(GetMemSize resultVar memRegion)
+  # ARGN holds all arguments to function after last named one
+  foreach(ITR ${ARGN})
+    if(ITR MATCHES "${memRegion}*")
+        string(FIND ${ITR} "=" index)
+        MATH(EXPR index "${index}+1")
+        string(SUBSTRING ${ITR} ${index} -1 value)
+        set(${resultVar} ${value} PARENT_SCOPE)
+        return()
+    endif()
+  endforeach()
+endmacro()
+
+GetMemSize(ram_size "MBED_CONF_TARGET_RAM_SIZE" ${MBED_CONFIG_DEFINITIONS})
+GetMemSize(boot_stack_size "MBED_CONF_TARGET_BOOT_STACK_SIZE" ${MBED_CONFIG_DEFINITIONS})
+GetMemSize(thread_stack_size "MBED_CONF_RTOS_MAIN_THREAD_STACK_SIZE" ${MBED_CONFIG_DEFINITIONS})
+MATH(EXPR total_ram_boot_stack_size "${ram_size}-${boot_stack_size}" OUTPUT_FORMAT HEXADECIMAL)
+MATH(EXPR total_boot_thread_stack_size "${boot_stack_size}+${thread_stack_size}" OUTPUT_FORMAT HEXADECIMAL)
+
+if(${total_ram_boot_stack_size} LESS_EQUAL ${total_boot_thread_stack_size})
+    set(TEST_SKIPPED "Insufficient stack for stack_size_unification tests")
+endif()
+
 mbed_greentea_add_test(
     TEST_NAME
         mbed-hal-stack-size-unification
+    TEST_INCLUDE_DIRS
+        .
     TEST_SOURCES
         main.cpp
+    TEST_SKIPPED
+        ${TEST_SKIPPED}
 )

hal/tests/TESTS/mbed_hal/stack_size_unification/main.cpp

@@ -20,7 +20,7 @@
 #include "unity.h"
 #include "utest.h"
 
-#ifdef TARGET_RENESAS
+#ifdef TARGET_CORTEX_A
 #error [NOT_SUPPORTED] Cortex-A target not supported for this test
 #else