Patch libblst to overcome duplicate symbol definition problem

Author: neilmayhew

overlays/crypto/libblst.nix

@@ -6,6 +6,8 @@ stdenv.mkDerivation rec {
 
   inherit src;
 
+  patches = [ ./libblst.patch ];
+
   # note on -D__BLST_PORTABLE__, this should allow us to have MULX, and similar
   # stuff run-time detected, and as such blst built on newer hardware should still
   # work on older. Notably Intel before Broadwell, and AMD before Ryzen, do not

overlays/crypto/libblst.patch

@@ -0,0 +1,16 @@
+diff --git a/src/cpuid.c b/src/cpuid.c
+index a1a01d4..bbba87e 100644
+--- a/src/cpuid.c
++++ b/src/cpuid.c
+@@ -5,9 +5,9 @@
+  */
+ 
+ #if (defined(__GNUC__) || defined(__clang__) || defined(__SUNPRO_C)) && !defined(_WIN32)
+-__attribute__((visibility("hidden")))
++__attribute__((visibility("hidden"), common))
+ #endif
+-int __blst_platform_cap = 0;
++int __blst_platform_cap;
+ 
+ #if defined(__x86_64__) || defined(__x86_64) || (defined(_M_X64) && !defined(_M_ARM64EC))
+