meson: explicitly annotate version.h as dependency

Currently we list the custom_target (aka vcs_tag() as part of the
sources. Although since it's not an explicit dependency meson/ninja are
free to compile the C/C++ files, before the file is generated.

Closes: https://github.com/flightlessmango/MangoHud/issues/862
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

meson.build

@@ -16,6 +16,8 @@ mangohud_version = vcs_tag(
   input:  'version.h.in',
   output: 'version.h')
 
+mangohud_version_dep = declare_dependency(sources : mangohud_version)
+
 pre_args = [
   '-D__STDC_CONSTANT_MACROS',
   '-D__STDC_FORMAT_MACROS',

src/meson.build

@@ -162,6 +162,7 @@ mangohud_static_lib = static_library(
     ],
   gnu_symbol_visibility : 'hidden',
   dependencies : [
+    mangohud_version_dep,
     vulkan_wsi_deps,
     dearimgui_dep,
     spdlog_dep,