Fix the typo: "desugar-classpath" to "desugar-bootclasspath"

Test: runs "m -j checkbuild tests cts", and then --bootclasspath_entry
shows up in desugar command.

Change-Id: Ibcc8a3f51438723151c57f79e5a1184350efbd30
diff --git a/core/definitions.mk b/core/definitions.mk
index d3277b5..235cf67 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -2515,7 +2515,7 @@
 $(if $(PRIVATE_JAR_MANIFEST), $(hide) echo unsupported options JAR_MANIFEST in $@; exit 53)
 endef
 
-define desugar-classpath
+define desugar-bootclasspath
 $(filter-out -classpath -bootclasspath "",$(subst :,$(space),$(1)))
 endef