On Windows, build ``bazel.exe`` instead of just ``bazel``.

Needed for #276.

--
MOS_MIGRATED_REVID=114693711
diff --git a/scripts/bootstrap/buildenv.sh b/scripts/bootstrap/buildenv.sh
index c2b30fa..63d0897 100755
--- a/scripts/bootstrap/buildenv.sh
+++ b/scripts/bootstrap/buildenv.sh
@@ -36,6 +36,13 @@
   MACHINE_IS_ARM='yes'
 fi
 
+# Extension for executables.
+EXE_EXT=""
+case "${PLATFORM}" in
+msys*|mingw*)
+  EXE_EXT=".exe"
+esac
+
 ATEXIT_=""
 function atexit() {
   ATEXIT_="$1; ${ATEXIT_}"
diff --git a/scripts/bootstrap/compile.sh b/scripts/bootstrap/compile.sh
index f9e6d31..9195e7a 100755
--- a/scripts/bootstrap/compile.sh
+++ b/scripts/bootstrap/compile.sh
@@ -31,9 +31,6 @@
 
 LDFLAGS=${LDFLAGS:-""}
 
-# Extension for executables (.exe on Windows).
-EXE_EXT=""
-
 MSYS_DLLS=""
 PATHSEP=":"
 
@@ -76,8 +73,6 @@
 msys*|mingw*)
   # Use a simplified platform string.
   PLATFORM="mingw"
-  # Workaround for msys issue which causes omission of std::to_string.
-  EXE_EXT=".exe"
   PATHSEP=";"
   # Find the latest available version of the SDK.
   JAVA_HOME="${JAVA_HOME:-$(ls -d /c/Program\ Files/Java/jdk* | sort | tail -n 1)}"