Add workaround for MacOS build issue

cmake/macos/buildspec.cmake

@@ -4,6 +4,36 @@ include_guard(GLOBAL)
 
 include(buildspec_common)
 
+# Hacky workaround to ensure all libobs headers are available at build time
+function(_check_for_libobs_headers)
+  set(dependencies_dir "${CMAKE_CURRENT_SOURCE_DIR}/.deps")
+
+  set(headers_to_copy "util/config-file.h" "util/platform.h"
+                      "graphics/matrix4.h" "graphics/axisang.h")
+
+  foreach(header IN LISTS headers_to_copy)
+    set(libobs_header_location
+        "${dependencies_dir}/Frameworks/libobs.framework/Versions/A/Headers/${header}"
+    )
+
+    if(EXISTS ${libobs_header_location})
+      continue()
+    endif()
+
+    string(
+      JSON
+      version
+      GET
+      ${buildspec}
+      dependencies
+      obs-studio
+      version)
+    set(input_file "${dependencies_dir}/obs-studio-${version}/libobs/${header}")
+    message(STATUS "Will copy ${input_file} to ${libobs_header_location} ...")
+    configure_file(${input_file} ${libobs_header_location} COPYONLY)
+  endforeach()
+endfunction()
+
 # _check_dependencies_macos: Set up macOS slice for _check_dependencies
 function(_check_dependencies_macos)
   set(arch universal)
@@ -32,3 +62,4 @@ function(_check_dependencies_macos)
 endfunction()
 
 _check_dependencies_macos()
+_check_for_libobs_headers()