Vulkan: Choose correct libvulkan on Android

Contrary to Linux, libvulkan.so on Android doesn't have the additional
.1 at the end (libvulkan.so.1 on Linux)

BUG=dawn:286

Change-Id: I22f06121b81e0fe08faae7d105a7c2094e788184
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/14104
Reviewed-by: David Turner <digit@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>

src/dawn_native/vulkan/BackendVk.cpp

diff --git a/src/dawn_native/vulkan/BackendVk.cpp b/src/dawn_native/vulkan/BackendVk.cpp
index 02b5b3a..06a2c34 100644
--- a/src/dawn_native/vulkan/BackendVk.cpp
+++ b/src/dawn_native/vulkan/BackendVk.cpp
@@ -22,11 +22,15 @@
 
 #include <iostream>
 
-#if DAWN_PLATFORM_LINUX
+#if defined(DAWN_PLATFORM_LINUX)
+#    if defined(DAWN_PLATFORM_ANDROID)
+const char kVulkanLibName[] = "libvulkan.so";
+#    else
 const char kVulkanLibName[] = "libvulkan.so.1";
-#elif DAWN_PLATFORM_WINDOWS
+#    endif
+#elif defined(DAWN_PLATFORM_WINDOWS)
 const char kVulkanLibName[] = "vulkan-1.dll";
-#elif DAWN_PLATFORM_FUCHSIA
+#elif defined(DAWN_PLATFORM_FUCHSIA)
 const char kVulkanLibName[] = "libvulkan.so";
 #else
 #    error "Unimplemented Vulkan backend platform"