Do not add unoil.jar to manifest Class-Path

...it must implicitly be loaded by the UNO type manager classloader anyway (via
URE_MORE_JAVA_TYPES), so not explicitly mentioning it can help find problems
early should it /not/ already be loaded by the type manager classloader.

Change-Id: I35b4f2804b68a35682e93699840101a15317a096

solenv/gbuild/Jar.mk

@@ -217,8 +217,9 @@ $$(call gb_Output_error,\
  gb_Jar_add_jar: use gb_Jar_use_jar instead.)
 endef
 
-# URE jars are not added to manifest classpath
-gb_Jar_default_jars := $(gb_Jar_URE)
+# URE jars are not added to manifest classpath; and neither is unoil.jar, which
+# is available at runtime via URE_MORE_JAVA_TYPES:
+gb_Jar_default_jars := $(gb_Jar_URE) unoil
 
 # remember: classpath is "inherited" to ClassSet
 define gb_Jar_use_jar