Allow BUILD_HOST_static to build statically-linked emulator

Statically linked emulator is easy to setup in sandboxed environment.

With this and BUILD_HOST_static in build/ (seperate CL), statically-linked
SDK tools can be built with the following command

BUILD_HOST_static=1 make PRODUCT-sdk-aapt adb aidl dexdump fastboot \
  llvm-rs-cc dmtracedump emulator emulator-arm emulator-x86 \
  etc1tool hprof-conv mksdcard sqlite3 zipalign

No need to build HW GL libraries (libOpenglRender, libGLES_CM_translator,
libGLES_V2_translator and libEGL_translator) because statically-linked
emulator doesn't support audio and graphics. (eg. -no-window)

Change-Id: I209287a00f66295b8b8135451025428f03776a1a
diff --git a/Makefile.android b/Makefile.android
index 7b35039..ce5336f 100644
--- a/Makefile.android
+++ b/Makefile.android
@@ -129,6 +129,10 @@
       MY_LDLIBS += -m32
     endif
   endif
+
+  ifneq ($(BUILD_HOST_static),)
+    MY_LDLIBS += -static
+  endif
 endif
 
 # Enable warning, except those related to missing field initializers