Android: add all arch support

Add support for armv7a, i686 and x86_64 archs to android.mk
Add -fPIC to depends file as anddroid requires it see https://stackoverflow.com/questions/30498776/position-independent-executables-and-android

depends/packages/libevent.mk

@@ -19,6 +19,7 @@ define $(package)_set_vars
   $(package)_config_opts=--disable-shared --disable-openssl --disable-libevent-regress --disable-samples
   $(package)_config_opts_release=--disable-debug-mode
   $(package)_config_opts_linux=--with-pic
+  $(package)_config_opts_android=--with-pic
 endef
 
 define $(package)_config_cmds