RFR: JDK-8168607: langtools/test/Makefile should set -retain:fail,error by default

[Erik Joelsson]

This patch moves the langtools/test/Makefile one step closer being 
alignmened with the rest of the test/*/Makefiles by adding the 
-retain:fail,error jtreg option.

Bug: https://bugs.openjdk.java.net/browse/JDK-8168607

Patch:

diff -r ab39653a1e6d test/Makefile
--- a/test/Makefile
+++ b/test/Makefile
@@ -161,6 +161,9 @@
  JTREG_TESTVM_MEMORY_OPTION = -vmoption:-Xmx768m
  JTREG_OPTIONS += $(JTREG_TESTVM_MEMORY_OPTION)

+# Retain all files for failing tests
+JTREG_OPTIONS += -retain:fail,error
+
  ifdef EXTRA_JTREG_OPTIONS
    JTREG_OPTIONS += $(EXTRA_JTREG_OPTIONS)
  endif


/Erik