Don't use git submodule

.gitignore

@@ -5,3 +5,4 @@
 /priv/ecrecover.so
 /c_src/ecrecover.d
 /c_src/ecrecover.o
+/c_src/secp256k1

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "c_src/secp256k1"]
-	path = c_src/secp256k1
-	url = https://github.com/bitcoin-core/secp256k1.git

Makefile

@@ -0,0 +1,12 @@
+REBAR3 ?= $(shell test -e `which rebar3` 2>/dev/null && which rebar3 || echo "./rebar3")
+
+all: compile
+
+compile:
+	${REBAR3} compile
+
+clean:
+	${REBAR3} clean
+
+test: compile
+	${REBAR3} eunit

c_src/secp256k1

@@ -1 +0,0 @@
-Subproject commit cbe41ac138bc0773d60ab1942b7ad6fc5eccfc19

rebar.config

@@ -1,15 +1,7 @@
 {deps,
   [{sha3, {git, "https://github.com/aeternity/erlang-sha3", {ref, "b5f27a2"}}}]}.
 
-{pre_hooks, [ {compile, "git submodule update --init"}
-            , {"(linux|darwin)", compile, "sh -c \"cd c_src/secp256k1 && ./autogen.sh && ./configure --enable-module-recovery && make\""}
-            , {"win32", compile, "make -f Makefile.win32 win32_ecrecover"}
-            ]}.
-
-{post_hooks, [ {"(linux|darwin)", clean, "make -C \"c_src/secp256k1\" clean"}
-             , {"win32", clean, "make -f Makefile.win32 clean_win32_ecrecover"}
-             ]}.
-
+{pre_hooks, [ {compile, "./secp256k1.sh"} ]}.
 
 {plugins, [pc]}.
 

secp256k1.sh

@@ -0,0 +1,12 @@
+#! /bin/sh
+
+[ -f c_src/secp256k1/.libs/libsecp256k1.a ] && exit 0
+
+cd c_src
+git clone https://github.com/bitcoin/secp256k1
+cd secp256k1
+git -c advice.detachedHead=false checkout cbe41ac138bc0773d60ab1942b7ad6fc5eccfc19
+./autogen.sh
+./configure --enable-module-recovery
+make clean
+make