support vulkan headers for android (#918)

packages/v/vulkan-headers/xmake.lua

@@ -18,7 +18,7 @@ package("vulkan-headers")
       add_extsources("pacman::vulkan-headers")
     end
 
-    on_install("windows", "linux", "macosx", function (package)
+    on_install("windows", "linux", "macosx", "android", function (package)
         import("package.tools.cmake").install(package)
     end)
 

packages/v/vulkan-memory-allocator/xmake.lua

@@ -9,14 +9,14 @@ package("vulkan-memory-allocator")
 
     add_deps("vulkan-headers")
 
-    on_install("windows", "linux", "macosx", function (package) 
+    on_install("windows", "linux", "macosx", "android", function (package)
         os.cp("src/vk_mem_alloc.h", package:installdir("include"))
     end)
 
-    on_test(function (package) 
+    on_test(function (package)
         assert(package:check_csnippets({test = [[
             void test() {
                 int version = VMA_VULKAN_VERSION;
             }
         ]]}, {includes = "vk_mem_alloc.h"}))
-    end)
+    end)