Modify TMPDIR to avoid port colissions

Author: blorente

java/gazelle/testdata/gazelle_build_mode.bzl

@@ -27,13 +27,21 @@ def _gazelle_embedded_javaparser_impl(ctx):
 # Therefore, we have to look in the runfiles dir for the real gazelle binary.
 mkdir $RUNFILES_DIR/hack_for_runtime_path
 export GAZELLE_JAVA_JAVAHOME="$RUNFILES_DIR/hack_for_runtime_path/{java_home}"
+
+# If both the embedded and non-embedded version of a test are running at the same time, they will collide trying to create the port file and crash.
+export TMPDIR="$TMPDIR_embedded"
+
 exec $RUNFILES_DIR/_main/{gazelle_bin} "$@"
     """
 
     gazelle_runner_script_windows = """@echo off
 REM Because java_home points to ../<java_repository> but we pass the JDK runfiles in DefaultInfo,
 REM we insert a non-existent directory to cancel out the `..`.
 set "GAZELLE_JAVA_JAVAHOME=%RUNFILES_DIR%\\hack_for_runtime_path\\{java_home}"
+
+REM If both the embedded and non-embedded version of a test are running at the same time, they will collide trying to create the port file and crash.
+set "TMPDIR=%TMPDIR%_embedded"
+
 call %RUNFILES_DIR%\\_main\\{gazelle_bin} %*
 """