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/zeromq.mk

@@ -10,6 +10,7 @@ define $(package)_set_vars
   $(package)_config_opts += --without-libsodium --without-libgssapi_krb5 --without-pgm --without-norm --without-vmci
   $(package)_config_opts += --disable-libunwind --disable-radix-tree --without-gcov
   $(package)_config_opts_linux=--with-pic
+  $(package)_config_opts_android=--with-pic
   $(package)_cxxflags=-std=c++11
 endef