Merge bitcoin#32357: depends: Fix cross-compiling qt package from macOS to Windows

35e57fb depends: Fix cross-compiling `qt` package from macOS to Windows (Hennadii Stepanov)

Pull request description:

  Native packages cannot be used during cross-compiling. However, Qt still unconditionally tries to find them, which causes issues in some cases, such as when [cross-compiling from macOS to Windows](bitcoin#32346).

  This PR explicitly disables this unnecessary Qt behaviour.

  Fixes bitcoin#32346.

  Here is a full workflow on my macOS Sequoia 15.4.1 (Intel):
  ```
  % brew install make cmake ninja mingw-w64 nsis
  % gmake -C depends -j 10 HOST=x86_64-w64-mingw32
  % cmake -B build --toolchain depends/x86_64-w64-mingw32/toolchain.cmake
  % cmake --build build -j 10 -t deploy
  ```

ACKs for top commit:
  shahsb:
    ACK bitcoin@35e57fb
  fanquake:
    ACK 35e57fb

Tree-SHA512: 2822fb49bc84dd094dbd189d8a9ca0f023e1e48127db7beaefb9db92de53df63bb0f399c9c430c33941f9a9ee6976b9161d80467d889f7717385b9d1ea9fee43

Author: fanquake

depends/packages/qt.mk

@@ -190,6 +190,14 @@ ifneq ($(host),$(build))
 $(package)_cmake_opts += -DCMAKE_SYSTEM_NAME=$($(host_os)_cmake_system_name)
 $(package)_cmake_opts += -DCMAKE_SYSTEM_VERSION=$($(host_os)_cmake_system_version)
 $(package)_cmake_opts += -DCMAKE_SYSTEM_PROCESSOR=$(host_arch)
+# Native packages cannot be used during cross-compiling. However,
+# Qt still unconditionally tries to find them, which causes issues
+# in some cases, such as when cross-compiling from macOS to Windows.
+# Explicitly disable this unnecessary Qt behaviour.
+$(package)_cmake_opts += -DCMAKE_DISABLE_FIND_PACKAGE_Libb2=TRUE
+$(package)_cmake_opts += -DCMAKE_DISABLE_FIND_PACKAGE_WrapSystemDoubleConversion=TRUE
+$(package)_cmake_opts += -DCMAKE_DISABLE_FIND_PACKAGE_WrapSystemMd4c=TRUE
+$(package)_cmake_opts += -DCMAKE_DISABLE_FIND_PACKAGE_WrapZSTD=TRUE
 endif
 ifeq ($(host_os),darwin)
 $(package)_cmake_opts += -DCMAKE_INSTALL_NAME_TOOL=true