fix two standalone tests on windows

test/standalone/empty_env/build.zig

@@ -7,7 +7,7 @@ pub fn build(b: *std.Build) void {
 
     const optimize: std.builtin.OptimizeMode = .Debug;
 
-    if (builtin.os.tag == .windows and std.process.hasEnvVarConstant("ConEmuHWND")) {
+    if (builtin.os.tag == .windows and b.graph.environ_map.contains("ConEmuHWND")) {
         // ConEmu injects environment variables into processes before they are executed
         // depending on user settings. This obviously invalidates the test, so skipping
         // it is the best option.

test/standalone/windows_argv/build.zig

@@ -67,7 +67,7 @@ pub fn build(b: *std.Build) !void {
 
     // Only target the MSVC ABI if MSVC/Windows SDK is available
     const has_msvc = has_msvc: {
-        const sdk = std.zig.WindowsSdk.find(b.allocator, b.graph.io, builtin.cpu.arch) catch |err| switch (err) {
+        const sdk = std.zig.WindowsSdk.find(b.allocator, b.graph.io, builtin.cpu.arch, &b.graph.environ_map) catch |err| switch (err) {
             error.OutOfMemory => @panic("oom"),
             else => break :has_msvc false,
         };