Stop linking libdl.a into static bins

libdl.a has a no-op dlopen, which breaks static libraries that need a real
dlopen. Instead of automatically linking libdl.a into static executables,
make it optional.

Until recently, the libunwind_llvm.a unwinder, used on arm32, needed the
no-op dladdr, but it's now built using -D_LIBUNWIND_USE_DLADDR=0.

The HWASan run-time uses dlsym and dladdr, so add a libdl dependency for
HWASan-built static binaries. We could also remove the dependency from
libclang_rt.hwasan_static-*.a, but this is also easy to do.

Bug: http://b/141485154
Test: bionic unit tests, device boots, verify that static and dynamic
   executables can throw/catch an exception
Test: verify that a static executable using dlopen doesn't link (unless it
   adds an explicit dependency on libdl)

Change-Id: Ic52c3f336b671b4ed335e99c94a64dfe8614b618

cc/sanitize.go

@@ -848,12 +848,14 @@ func sanitizerRuntimeMutator(mctx android.BottomUpMutatorContext) {
 
 		// Determine the runtime library required
 		runtimeLibrary := ""
+		var extraStaticDeps []string
 		toolchain := c.toolchain(mctx)
 		if Bool(c.sanitize.Properties.Sanitize.Address) {
 			runtimeLibrary = config.AddressSanitizerRuntimeLibrary(toolchain)
 		} else if Bool(c.sanitize.Properties.Sanitize.Hwaddress) {
 			if c.staticBinary() {
 				runtimeLibrary = config.HWAddressSanitizerStaticLibrary(toolchain)
+				extraStaticDeps = []string{"libdl"}
 			} else {
 				runtimeLibrary = config.HWAddressSanitizerRuntimeLibrary(toolchain)
 			}
@@ -887,7 +889,7 @@ func sanitizerRuntimeMutator(mctx android.BottomUpMutatorContext) {
 				mctx.AddFarVariationDependencies(append(mctx.Target().Variations(), []blueprint.Variation{
 					{Mutator: "link", Variation: "static"},
 					{Mutator: "image", Variation: c.imageVariation()},
-				}...), staticDepTag, runtimeLibrary)
+				}...), staticDepTag, append([]string{runtimeLibrary}, extraStaticDeps...)...)
 			} else if !c.static() && !c.header() {
 				// dynamic executable and shared libs get shared runtime libs
 				mctx.AddFarVariationDependencies(append(mctx.Target().Variations(), []blueprint.Variation{