fix(BLE): Pass Project Optimization Flag Down to Cordio

[Jake-Carter]

Pass Project Optimization Flag Down to Cordio

Description

MXC_OPTIMIZE_CFLAGS was not being passed down to the Cordio library build. Therefore, users had no easy way to change the optimization level of the library.

This PR passes down the project's optimization flags to Cordio. Users can individually set the optimization level for the library if needed.

!!This will change user's default Cordio builds from -Os to -Og!!

+# Allow user to set Cordio optimization level if needed
+CORDIO_OPTIMIZE_CFLAGS ?= ${MXC_OPTIMIZE_CFLAGS}
+
 # Add rule to build the Driver Library
 ${CORDIO_BUILD_DIR}/${CORDIO_LIB}: ${CORDIO_C_FILES} ${PROJECTMK}
        $(MAKE) -f ${CORDIO_DIR}/platform/targets/maxim/build/libCordio.mk lib MAXIM_PATH=${MAXIM_PATH} PROJECT=${CORDIO_LIB} \
        CORDIO_LIB_VAR=${CORDIO_LIB_VAR} BUILD_DIR=${CORDIO_BUILD_DIR} MFLOAT_ABI=$(MFLOAT_ABI) \
        DUAL_CORE=$(DUAL_CORE) RISCV_CORE=$(RISCV_CORE) TRACE=${TRACE} DEBUG=${DEBUG} RTOS=${RTOS} \
-       CFG_DEV="${CFG_DEV}" PROJECTMK=${PROJECTMK} BOARD=${BOARD}
+       CFG_DEV="${CFG_DEV}" PROJECTMK=${PROJECTMK} BOARD=${BOARD} MXC_OPTIMIZE_CFLAGS=${CORDIO_OPTIMIZE_CFLAGS}

I have 2 main concerns over this:

1. When end users re-build Cordio the debug behavior is consistent, but the optimization level for the library has changed. Therefore, the library is objectively different.
2. Developers building from source need to be aware of this change.

Alternative Implementation

Alternatively, the following implementation preserves -Os as the default at the following tradeoffs:

1. When users re-build the library from source, debug behavior could be inconsistent
2. Developers and users must manage another variable unique to the Cordio library.
3. Mismatch between project optimization and Cordio optimization
4. Projects build with DEBUG=1 by default. This will add debug flags (-g -ggdb -DDEBUG to Cordio resulting in a 13KB library size increase, but debug behavior could still remain inconsistent with -Os. This is debatably a larger issue that may need to be addressed separately.

+# Allow user to set Cordio optimization level if needed
+CORDIO_OPTIMIZE_CFLAGS ?= -Os
+
 # Add rule to build the Driver Library
 ${CORDIO_BUILD_DIR}/${CORDIO_LIB}: ${CORDIO_C_FILES} ${PROJECTMK}
        $(MAKE) -f ${CORDIO_DIR}/platform/targets/maxim/build/libCordio.mk lib MAXIM_PATH=${MAXIM_PATH} PROJECT=${CORDIO_LIB} \
        CORDIO_LIB_VAR=${CORDIO_LIB_VAR} BUILD_DIR=${CORDIO_BUILD_DIR} MFLOAT_ABI=$(MFLOAT_ABI) \
        DUAL_CORE=$(DUAL_CORE) RISCV_CORE=$(RISCV_CORE) TRACE=${TRACE} DEBUG=${DEBUG} RTOS=${RTOS} \
-       CFG_DEV="${CFG_DEV}" PROJECTMK=${PROJECTMK} BOARD=${BOARD}
+       CFG_DEV="${CFG_DEV}" PROJECTMK=${PROJECTMK} BOARD=${BOARD} MXC_OPTIMIZE_CFLAGS=${CORDIO_OPTIMIZE_CFLAGS}

[lorne-maxim]

I prefer the first implementation outlined in this PR's description.