Visibility PR broke building with Tracy enabled

[KristofferC]

Errors with:

/Users/kristoffercarlsson/julia/src/timing.c:28:1: error: visibility does not match previous declaration
JL_DLLEXPORT uint64_t jl_timing_enable_mask = ~((1ull << JL_TIMING_ROOT) |
^
/Users/kristoffercarlsson/julia/src/support/dtypes.h:89:23: note: expanded from macro 'JL_DLLEXPORT'
# define JL_DLLEXPORT JL_DLLIMPORT
                      ^
/Users/kristoffercarlsson/julia/src/support/dtypes.h:85:38: note: expanded from macro 'JL_DLLIMPORT'
#define JL_DLLIMPORT __attribute__ ((visibility("default")))
                                     ^
./julia_internal.h:29:13: note: previous attribute is here
#pragma GCC visibility push(hidden)
            ^
/Users/kristoffercarlsson/julia/src/timing.c:38:1: error: visibility does not match previous declaration
JL_DLLEXPORT uint64_t jl_timing_counts[(int)JL_TIMING_LAST] = {0};
^
/Users/kristoffercarlsson/julia/src/support/dtypes.h:89:23: note: expanded from macro 'JL_DLLEXPORT'
# define JL_DLLEXPORT JL_DLLIMPORT
                      ^
/Users/kristoffercarlsson/julia/src/support/dtypes.h:85:38: note: expanded from macro 'JL_DLLIMPORT'
#define JL_DLLIMPORT __attribute__ ((visibility("default"))

Ref #49600

cc @vtjnash

[vtjnash]

Looks like it was being declared in the wrong place (JL_DLLEXPORT should go in headers, and is optional to duplicate in the source code file). We are a bit more strict about getting that right after #49600, as usually the linker would previously usually accept errors by generating extra stub code to work around it.