Convert output to Intel HEX format unconditionally in post-build

This converts output to Intel HEX format unconditionally but to BIN
format just on demand for the following reasons:
1. Most flash programming tools support Intel HEX format, e.g. GDB
   load command.
2. Output can have large holes in addresses which BIN format cannot
   handle and can generate very large file.

Author: ccli8

tools/cmake/mbed_target_functions.cmake

@@ -13,19 +13,24 @@ function(mbed_generate_bin_hex target)
 
     set(artifact_name $<TARGET_FILE_BASE_NAME:${target}>)
 
+    # Convert to BIN format just on demand because the resultant output
+    # can have large holes in addresses which BIN format cannot handle and
+    # can generate very large file.
+    #
     # The first condition is quoted in case MBED_OUTPUT_EXT is unset
     if ("${MBED_OUTPUT_EXT}" STREQUAL "" OR MBED_OUTPUT_EXT STREQUAL "bin")
         list(APPEND CMAKE_POST_BUILD_COMMAND
             COMMAND ${elf_to_bin} -O binary $<TARGET_FILE:${target}> ${CMAKE_CURRENT_BINARY_DIR}/${artifact_name}.bin
             COMMAND ${CMAKE_COMMAND} -E echo "-- built: ${CMAKE_CURRENT_BINARY_DIR}/${artifact_name}.bin"
         )
     endif()
-    if ("${MBED_OUTPUT_EXT}" STREQUAL "" OR MBED_OUTPUT_EXT STREQUAL "hex")
-        list(APPEND CMAKE_POST_BUILD_COMMAND
-            COMMAND ${elf_to_bin} -O ihex $<TARGET_FILE:${target}> ${CMAKE_CURRENT_BINARY_DIR}/${artifact_name}.hex
-            COMMAND ${CMAKE_COMMAND} -E echo "-- built: ${CMAKE_CURRENT_BINARY_DIR}/${artifact_name}.hex"
-        )
-    endif()
+    # Convert to Intel HEX format unconditionally which most flash programming
+    # tools can support. For example, GDB load command supports Intel HEX format
+    # but no BIN format.
+    list(APPEND CMAKE_POST_BUILD_COMMAND
+        COMMAND ${elf_to_bin} -O ihex $<TARGET_FILE:${target}> ${CMAKE_CURRENT_BINARY_DIR}/${artifact_name}.hex
+        COMMAND ${CMAKE_COMMAND} -E echo "-- built: ${CMAKE_CURRENT_BINARY_DIR}/${artifact_name}.hex"
+    )
 
     add_custom_command(
         TARGET