Interrupt Vector Table Setup

Write the startup vector table and reset handler for a Cortex-M device, including the initial stack pointer and the data and bss initialisation.

Constraints

• First word is the initial stack pointer, second is the reset handler.
• Copy .data from flash to RAM.
• Zero the .bss section.
• Call SystemInit then main.
• Provide a default handler that loops forever.
• Weak aliases so a C file can override any handler.