libvulkan: Return error if an unsupported instance extension is requested

Change-Id: I93d4a2a0b991682160c0ffe401f2b2b19f6e2be3
(cherry picked from commit 8a69c0845de6884377da2221ae3272b8dac03d55)
diff --git a/vulkan/tools/vkinfo.cpp b/vulkan/tools/vkinfo.cpp
index a2f4e8f..6a63667 100644
--- a/vulkan/tools/vkinfo.cpp
+++ b/vulkan/tools/vkinfo.cpp
@@ -202,10 +202,11 @@
                                     &info->layer_extensions[i]);
     }
 
-    const std::array<const char*, 1> kDesiredExtensions = {
-        {VK_EXT_DEBUG_REPORT_EXTENSION_NAME},
+    const char* kDesiredExtensions[] = {
+        VK_EXT_DEBUG_REPORT_EXTENSION_NAME,
     };
-    const char* extensions[kDesiredExtensions.size()];
+    const char*
+        extensions[sizeof(kDesiredExtensions) / sizeof(kDesiredExtensions[0])];
     uint32_t num_extensions = 0;
     for (const auto& desired_ext : kDesiredExtensions) {
         bool available = HasExtension(info->extensions, desired_ext);