fix: Add C shim for static context to address Windows MinGW64 runtime failure

This change attempts to address a Windows MinGW64 runtime failure that occurs during
testing, where we see a "32 bit pseudo relocation out of range" error. The error
suggests an issue with how GHC handles pointers in Windows executables.

1. Adds a C shim (hs_secp256k1_shim.c) to handle the static context
2. Updates the Haskell FFI bindings to use the shim instead of direct access
3. Bumps version to 0.3.1 to reflect the FFI interface change

Author: prolic

cbits/hs_secp256k1_shim.c

@@ -0,0 +1,7 @@
+#include <secp256k1.h>
+
+/* Returns the adress of the library's built-in context */
+const secp256k1_context* hs_secp256k1_content_static(void)
+{
+    return secp256k1_context_static;
+}

libsecp256k1.cabal

@@ -5,7 +5,7 @@ cabal-version: 1.12
 -- see: https://github.com/sol/hpack
 
 name:           libsecp256k1
-version:        0.2.1
+version:        0.3.1
 synopsis:       Bindings for secp256k1
 description:    Sign and verify signatures using the secp256k1 library.
 category:       Crypto
@@ -35,6 +35,8 @@ library
       Paths_libsecp256k1
   hs-source-dirs:
       src
+  c-sources:
+      cbits/hs_secp256k1_shim.c
   default-extensions:
       ImportQualifiedPost
   pkgconfig-depends:

package.yaml

@@ -1,5 +1,5 @@
 name: libsecp256k1
-version: 0.2.1
+version: 0.3.1
 synopsis: Bindings for secp256k1
 description: Sign and verify signatures using the secp256k1 library.
 category: Crypto

src/Crypto/Secp256k1/Prim.hs

@@ -302,8 +302,12 @@ foreign import capi safe "secp256k1.h secp256k1_context_destroy"
 --  type serialization/parsing functions which require a context object to maintain
 --  API consistency, but currently do not require expensive precomputations or dynamic
 --  allocations.
-foreign import ccall unsafe "secp256k1.h secp256k1_context_no_precomp"
-    contextNoPrecomp :: Ctx
+foreign import ccall unsafe "hs_secp256k1_content_static"
+    c_contextStatic :: IO Ctx
+
+{-# NOINLINE contextStatic #-}
+contextStatic :: Ctx
+contextStatic = unsafePerformIO c_contextStatic
 
 
 -- | Copy a secp256k1 context object into caller-provided memory.
@@ -445,7 +449,7 @@ foreign import capi safe "secp256k1.h secp256k1_context_set_error_callback"
 --  undefined.
 --
 --  When this function has not been called (or called with fn==NULL), then the
---  default handler will be used. The library provides a default handler which
+--  default handler will be used. The library provides a default handler which
 --  writes the message to stderr and calls abort. This default handler can be
 --  replaced at link time if the preprocessor macro
 --  USE_EXTERNAL_DEFAULT_CALLBACKS is defined, which is the case if the build