Add a "used" attribute to __vector_handlers to fix ARMC6 build with
the "-flto" flag.
(Error: L6236E: No section matches selector - no section to be FIRST/LAST. )
This attribute, attached to a function/variable, means that code must be emitted
for the function even if it appears that the function is not referenced.
Add a "used" attribute to Reset_Handler_Cascade to fix GCC build with
the "-flto" flag.
This attribute, attached to a function, means that code must be emitted
for the function even if it appears that the function is not referenced.
1. With mbed OS 5, mbed_sdk_init() is ensured to call before C++ global object constructor.
2. Refine startup file with GCC_ARM toolchain related to this modification.