ci/win: merge 'build.sh' into workflow

.github/build.sh

@@ -1,15 +0,0 @@
-#!/usr/bin/env bash
-
-wrap_task() {
-  echo "::group::$@"
-  "$@"
-  echo '::endgroup::'
-}
-
-wrap_task ./autoconf.sh
-wrap_task ./configure
-wrap_task make install
-
-which iverilog
-
-wrap_task make check

.github/workflows/test.yml

@@ -62,8 +62,14 @@ jobs:
           mingw-w64-x86_64-toolchain
         update: true
 
-    - name: Build
-      run: ./.github/build.sh
+    - name: Build, install and check
+      run: |
+        wrap() { echo "::group::$@"; "$@"; echo '::endgroup::'; }
+        wrap ./autoconf.sh
+        wrap ./configure
+        wrap make install
+        which iverilog
+        wrap make check
 
     - name: Test
       run: ./.github/test.sh