% cat -n jdk/makefiles/Tools.gmk
    [...]
    26 # Cache all finds needed for this file. Only used on windows.
    27 $(eval $(call FillCacheFind,$(JDK_TOPDIR)/make/tools \
    28 $(JDK_TOPDIR)/src/solaris/classes \
    29 $(JDK_TOPDIR)/makefiles/sun))

Given that FillCacheFind is Windows only, line 28 should most likely read like this:

     $(JDK_TOPDIR)/src/share/classes \