Add DLL-loading head <android/utils/dll.h>

This patch adds several functions to make loading shared libraries
dynamically easier. This will be used to load the GLES emulation
libraries.

Change-Id: Ib401af339530bc647bfa86fb23a2840fe0a201dd
diff --git a/Makefile.common b/Makefile.common
index 2179ae7..5d1aa6e 100644
--- a/Makefile.common
+++ b/Makefile.common
@@ -110,6 +110,7 @@
 	android/utils/assert.c \
 	android/utils/bufprint.c \
 	android/utils/debug.c \
+	android/utils/dll.c \
 	android/utils/dirscanner.c \
 	android/utils/filelock.c \
 	android/utils/ini.c \