Add libstagefright_soft_flacdec to core_base.mk

Test: Play test file from b/37787245
Bug: 37794552
Change-Id: Ib5e4a26b9650e92047587d2e98f992c2df57eede
diff --git a/target/product/core_base.mk b/target/product/core_base.mk
index e0a20b8..151e8de 100644
--- a/target/product/core_base.mk
+++ b/target/product/core_base.mk
@@ -43,6 +43,7 @@
     libstagefright_soft_amrwbenc \
     libstagefright_soft_avcdec \
     libstagefright_soft_avcenc \
+    libstagefright_soft_flacdec \
     libstagefright_soft_flacenc \
     libstagefright_soft_g711dec \
     libstagefright_soft_gsmdec \