selectively increase optimization -Os -> -O2

- targetted at modules/libraries that benefit without drastically
increasing flash usage
 - ignored on boards with CONSTRAINED_FLASH set

src/modules/mc_rate_control/CMakeLists.txt

@@ -37,6 +37,7 @@ px4_add_module(
 	MODULE modules__mc_rate_control
 	MAIN mc_rate_control
 	COMPILE_FLAGS
+		${MAX_CUSTOM_OPT_LEVEL}
 	SRCS
 		MulticopterRateControl.cpp
 		MulticopterRateControl.hpp

src/modules/mc_rate_control/RateControl/CMakeLists.txt

@@ -33,12 +33,10 @@
 
 px4_add_library(RateControl
 	RateControl.cpp
+	RateControl.hpp
 )
-target_include_directories(RateControl
-	PUBLIC
-	${CMAKE_CURRENT_SOURCE_DIR}
-)
-
+target_compile_options(RateControl PRIVATE ${MAX_CUSTOM_OPT_LEVEL})
+target_include_directories(RateControl PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
 target_link_libraries(RateControl PRIVATE mathlib)
 
 px4_add_unit_gtest(SRC RateControlTest.cpp LINKLIBS RateControl)