Remove internal Runtime APEX library that shouldn't be in system.

(cherry picked from commit c36f2fa9688ebd034a071d878f2cc15be86a64d2)

Bug: 132289438
Merged-In: I4e826afe69acc8c99599e6f7626588009b493691
Change-Id: I770b4ae2efac433e58411ee38d3a70a09edd3f6b
diff --git a/uml.mk b/uml.mk
index 659242d..03db5e9 100644
--- a/uml.mk
+++ b/uml.mk
@@ -71,7 +71,6 @@
     libm \
     libpixelflinger \
     libpower \
-    libsigchain \
     libstdc++ \
     libsurfaceflinger \
     libsysutils \