[loader] Add explicit (void) prototypes in loader_fuchsia.h

Specify (void) for fuchsia_initialize and fuchsia_teardown declarations
so C callers have complete prototype information when building with
-fexperimental-call-graph-section (-Wcall-graph-section-no-prototype).

Bug: 536931943
Change-Id: If6e3c03a3b5b5d19569f682d8c4e4e0716712671
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/Vulkan-Loader/+/1835149
Commit-Queue: Prabhu Karthikeyan Rajasekaran <prabhukr@google.com>
Reviewed-by: Craig Stout <cstout@google.com>

loader/loader_fuchsia.h

diff --git a/loader/loader_fuchsia.h b/loader/loader_fuchsia.h
index 0d4f7d0..d7a144a 100644
--- a/loader/loader_fuchsia.h
+++ b/loader/loader_fuchsia.h
@@ -26,8 +26,8 @@
 int get_manifest_fs_fd(void);
 
 // Called on loader shared library construction.
-void fuchsia_initialize();
+void fuchsia_initialize(void);
 // Called on loader shared library destruction.
-void fuchsia_teardown();
+void fuchsia_teardown(void);
 
 __END_CDECLS