Merge bitcoin/bitcoin#25322: build: Fix `capnp` package build for Android

8b8edc25c1 build: Specify native binaries explicitly when building `capnp` package (Hennadii Stepanov)
a413595c37 build: Fix `capnp` package build for Android (Hennadii Stepanov)

Pull request description:

  On master (e3c08eb620):
  ```
  $ make -C depends capnp MULTIPROCESS=1 HOST=aarch64-linux-android ANDROID_SDK=$ANDROID_HOME ANDROID_NDK=$ANDROID_HOME/ndk/23.2.8568313 ANDROID_API_LEVEL=28 ANDROID_TOOLCHAIN_BIN=$ANDROID_HOME/ndk/23.2.8568313/toolchains/llvm/prebuilt/linux-x86_64/bin
  ...
  ld: error: unable to find library -lkj
  ...
  ```

  This PR fixes this error, and also improves configuring according to the docs.

ACKs for top commit:
  ryanofsky:
    Code review ACK 8b8edc25c1. I'd be a little curious to know what causes the error and how `--disable-shared` fixes it, but these changes all look good

Tree-SHA512: 1b07b75f2a83932d8dc1f007e42a67d8327bd5fe4566f554dab4599e2a1e04b0144648790a1fd2ab1c295dba728586035aa0ebdbe5cf49df048ec87736895aaf

depends/packages/capnp.mk

@@ -6,8 +6,15 @@ $(package)_file_name=$(native_$(package)_file_name)
 $(package)_sha256_hash=$(native_$(package)_sha256_hash)
 $(package)_dependencies=native_$(package)
 
+define $(package)_set_vars :=
+$(package)_config_opts := --with-external-capnp
+$(package)_config_opts += CAPNP="$$(native_capnp_prefixbin)/capnp"
+$(package)_config_opts += CAPNP_CXX="$$(native_capnp_prefixbin)/capnp-c++"
+$(package)_config_opts_android := --disable-shared
+endef
+
 define $(package)_config_cmds
-  $($(package)_autoconf) --with-external-capnp
+  $($(package)_autoconf)
 endef
 
 define $(package)_build_cmds