build: disable qt SDK version checking

This tries to invoke xcrun, which is not available when cross-compiling.
Given we are in control of the SDK versions being used, removing this
check has minimal-no effect.

depends/packages/qt.mk

@@ -8,7 +8,7 @@ $(package)_linux_dependencies=freetype fontconfig libxcb libxkbcommon
 $(package)_qt_libs=corelib network widgets gui plugins testlib
 $(package)_patches=fix_qt_pkgconfig.patch mac-qmake.conf fix_no_printer.patch no-xlib.patch
 $(package)_patches+= fix_android_qmake_conf.patch fix_android_jni_static.patch dont_hardcode_pwd.patch
-$(package)_patches+= drop_lrelease_dependency.patch
+$(package)_patches+= drop_lrelease_dependency.patch no_sdk_version_check.patch
 $(package)_patches+= fix_qpainter_non_determinism.patch
 
 $(package)_qttranslations_file_name=qttranslations-$($(package)_suffix)
@@ -225,6 +225,7 @@ define $(package)_preprocess_cmds
   patch -p1 -i $($(package)_patch_dir)/fix_android_jni_static.patch && \
   patch -p1 -i $($(package)_patch_dir)/no-xlib.patch && \
   patch -p1 -i $($(package)_patch_dir)/fix_qpainter_non_determinism.patch &&\
+  patch -p1 -i $($(package)_patch_dir)/no_sdk_version_check.patch && \
   sed -i.old "s|updateqm.commands = \$$$$\$$$$LRELEASE|updateqm.commands = $($(package)_extract_dir)/qttools/bin/lrelease|" qttranslations/translations/translations.pro && \
   mkdir -p qtbase/mkspecs/macx-clang-linux &&\
   cp -f qtbase/mkspecs/macx-clang/qplatformdefs.h qtbase/mkspecs/macx-clang-linux/ &&\

depends/patches/qt/no_sdk_version_check.patch

@@ -0,0 +1,20 @@
+commit f5eb142cd04be2bc4ca610ed3b5b7e8ce3520ee3
+Author: fanquake <[email protected]>
+Date:   Tue Jan 5 16:08:49 2021 +0800
+
+    Don't invoke macOS SDK version checking
+
+    This tries to use xcrun which is not available when cross-compiling.
+
+diff --git a/qtbase/mkspecs/features/mac/default_post.prf b/qtbase/mkspecs/features/mac/default_post.prf
+index 92a9112bca6..447e186eb26 100644
+--- a/qtbase/mkspecs/features/mac/default_post.prf
++++ b/qtbase/mkspecs/features/mac/default_post.prf
+@@ -8,7 +8,6 @@ contains(TEMPLATE, .*app) {
+     !macx-xcode:if(isEmpty(BUILDS)|build_pass) {
+         # Detect changes to the platform SDK
+         QMAKE_EXTRA_VARIABLES += QMAKE_MAC_SDK QMAKE_MAC_SDK_VERSION QMAKE_XCODE_DEVELOPER_PATH
+-        QMAKE_EXTRA_INCLUDES += $$shell_quote($$PWD/sdk.mk)
+     }
+
+     # Detect incompatible SDK versions