sched_profil: Move static variable to block scope for MISRA C 2012 compliance

[hujun260]

Summary

Move the static g_prof variable declaration to block scope within the profil()
function when CONFIG_SMP is disabled, to comply with MISRA C 2012 Rule 8.9 which
requires objects used by only one function to be declared within that function's scope.

Motivation and Problem

MISRA C 2012 Rule 8.9 enforces improved code locality by requiring that objects
with internal linkage be declared at the smallest possible scope. The original
code declared g_prof at file scope globally, even though it is only used within
the profil() function when CONFIG_SMP is not enabled. When CONFIG_SMP is enabled,
g_prof is used in SMP call data initialization, requiring file-scope visibility.
This change optimizes the scope based on build configuration, improving code clarity
and compliance with embedded systems coding standards.

Changes

• Remove unconditional file-scope static struct profinfo_s g_prof declaration
• Add conditional CONFIG_SMP block at file scope containing g_prof and g_call_data
• Add local static struct profinfo_s g_prof declaration inside profil() function
  when CONFIG_SMP is disabled, restricting scope to only where it's used

Impact

• MISRA Compliance: Achieves MISRA C 2012 Rule 8.9 compliance for scope management
• Code Quality: Improves code locality and reduces global variable exposure
• Maintainability: Clearer intent about variable usage within build configurations
• Verifiability: Easier static analysis with properly scoped variables
• Backward Compatibility: No functional changes; identical runtime behavior
• Performance: No performance impact; scope changes are compile-time only

Verification

• Code compiles without warnings on ARM GCC 10.x
• Verified on QEMU ARMv7-A simulator with CONFIG_SMP disabled and enabled
• Profiling functionality verified in both SMP and non-SMP configurations
• Timer handler and profil function behavior unchanged
• SMP-specific code paths verified in CONFIG_SMP builds
• Static analysis shows improved compliance metrics

Testing

Tested with:

• ARM GCC 10.x compiler
• QEMU ARMv7-A simulation
• Profiling scenarios:
  • Non-SMP configuration (g_prof in profil() function scope)
  • SMP configuration (g_prof at file scope with g_call_data)
  • Timer handler invocation and profiling data collection
  • Scale and offset parameter handling

Files Changed

• sched/sched/sched_profil.c (6 lines: 4 insertions, 2 deletions)