Add duckdb patch signature_capi

Signature of capi extensions changed from returning void to returning a boolean,
mismatch on native targets is fine, since result is just ignored, but flagged
problems in wasm validation. Given capi extensions are still experimental, and
more so in duckdb-wasm, I would propose taking this liberty from DuckDB source
code to allow more simpler exploration on this matter.

patches/duckdb/signature_capi.patch

@@ -0,0 +1,13 @@
+diff --git a/src/main/extension/extension_load.cpp b/src/main/extension/extension_load.cpp
+index 59fc4e8cd9..b0282a7103 100644
+--- a/src/main/extension/extension_load.cpp
++++ b/src/main/extension/extension_load.cpp
+@@ -119,7 +119,7 @@ struct ExtensionAccess {
+ // The C++ init function
+ typedef void (*ext_init_fun_t)(DatabaseInstance &);
+ // The C init function
+-typedef void (*ext_init_c_api_fun_t)(duckdb_extension_info info, duckdb_extension_access *access);
++typedef bool (*ext_init_c_api_fun_t)(duckdb_extension_info info, duckdb_extension_access *access);
+ typedef const char *(*ext_version_fun_t)(void);
+ typedef bool (*ext_is_storage_t)(void);
+