Fix debug locations for Proc pointers

[HertzDevil]

A ProcPointer expands to a ProcLiteral:

def f
  puts caller.join("\n")
end

(->f).call
# becomes:
-> { f }.call

This ProcLiteral actually wraps a Def:

def ->
  f
end

But that Def does not have a location set, so debug locations become incorrect since #10934:

(->f).call
# => test.cr:2:8 in 'f'
# => src/time/location/loader.cr:2:22 in '~procProc(Nil)'
# => src/primitives.cr:266:3 in '__crystal_main'
# => src/crystal/main.cr:110:5 in 'main_user_code'
# ...

It can be seen from the following generated LLVM function corresponding the Def, which has no debug locations attached:

; Function Attrs: uwtable
define internal i32 @"~procProc(Nil)@test.cr:5"() #0 {
entry:
  %0 = call i32 @"*f:Nil"()
  ret i32 %0
}

This PR fixes that:

(->f).call
# => test.cr:2:8 in 'f'
# => test.cr:5:2 in '->'
# => src/primitives.cr:266:3 in '__crystal_main'
# => src/crystal/main.cr:110:5 in 'main_user_code'
# ...

[straight-shoota]

Would it be feasible to add a spec for this?

[sdogruyol]

Thank you @HertzDevil 🙏