Global variable declared/defined in the wrong file

[Daniel Páscoa]

This source file contains both declaration and definition of the variable. It is recommended to declare global variables in a header file and define them in separate source files. Please consider this best practice and move the declarations to a header file and corresponding definitions to respective source files.

Additional Notes:
LEON3_Boot_Cpu is a global variable and only used by start.S file. And as such cannot be declared as static. Because is used in an assembly file there was no need to declare it as external. But the global variable is in fact declared and defined in same file.

This ticket was raised as an outcome of the Independent SW Verification and Validation (ISVV) for ESA-promoted RTEMS SMP Qualification Data Packs (​https://rtems-qual.io.esa.int). Original ISVV reference for this issue is RTEMS-SMP-CODE-VER-043.

File list:
bsps\sparc\leon3\start\bspstart.c (line 54)

[Sebastian Huber <sebastian.huber@…>]

In b993111/rtems:

bsp/leon3: Move SMP data to start.S

The LEON3_Boot_Cpu global object is only used by start.S. Move the definition
of this object to start.S and use a local symbol .Lbootcpuindex for it.

Use a compare-and-swap instruction to assign the boot CPU. This allows a
concurrent initialization.

Close #4845.