fix Erlang's os:cmd, by adding @TERMUX_PREFIX@ so /bin/sh works

packages/erlang/prefix.patch

@@ -0,0 +1,13 @@
+diff --git a/lib/kernel/src/os.erl b/lib/kernel/src/os.erl
+index 29a26674ba..e6ab453a70 100644
+--- a/lib/kernel/src/os.erl
++++ b/lib/kernel/src/os.erl
+@@ -294,7 +294,7 @@ mk_cmd({win32,Wtype}, Cmd) ->
+ mk_cmd(_,Cmd) ->
+     %% Have to send command in like this in order to make sh commands like
+     %% cd and ulimit available
+-    {"/bin/sh -s unix:cmd", [out],
++    {"@TERMUX_PREFIX@/bin/sh -s unix:cmd", [out],
+      %% We insert a new line after the command, in case the command
+      %% contains a comment character.
+      %%