build: Add support for building dylibs.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@163412 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/make/options.mk b/make/options.mk
index f695fc8..d943e00 100644
--- a/make/options.mk
+++ b/make/options.mk
@@ -23,11 +23,20 @@
 # default.
 VISIBILITY_HIDDEN := 0
 
+# Whether the library is being built for kernel use.
+KERNEL_USE := 0
+
+# Whether the library should be built as a shared object.
+SHARED_LIBRARY := 0
+
 # Miscellaneous tools.
 
 AR := ar
 # FIXME: Remove these pipes once ranlib errors are fixed.
 ARFLAGS := cru 2> /dev/null
+
+LDFLAGS :=
+
 RANLIB := ranlib
 # FIXME: Remove these pipes once ranlib errors are fixed.
 RANLIBFLAGS := 2> /dev/null