Merge bitcoin/bitcoin#23675: build: Post-pr23489 small cleanups

ef81c51 build: Use config_opts instead of passing a compiler flag directly (Hennadii Stepanov)
3b8f4e3 build, qt: Drop unused CROSS_COMPILE variable for Android builds (Hennadii Stepanov)
e5a81e6 build, refactor: Re-use `qt_lib_suffix` variable (Hennadii Stepanov)

Pull request description:

  This PR suggests small cleanups as follow ups of bitcoin/bitcoin#23489.

ACKs for top commit:
  fanquake:
    ACK ef81c51

Tree-SHA512: c834c4f76218c7d567223c49bb86404b02facf61bc9be9a66a984ddd2b2f5e6150ba97071c993ea1faf4da10c87e81df292b3628d4407afccbe9df379ac452d7

Author: fanquake

build-aux/m4/bitcoin_qt.m4

@@ -161,7 +161,7 @@ AC_DEFUN([BITCOIN_QT_CONFIGURE],[
       _BITCOIN_QT_CHECK_STATIC_PLUGIN([QMacStylePlugin], [-lqmacstyle])
       AC_DEFINE([QT_QPA_PLATFORM_COCOA], [1], [Define this symbol if the qt platform is cocoa])
     elif test "$TARGET_OS" = "android"; then
-      QT_LIBS="-Wl,--export-dynamic,--undefined=JNI_OnLoad -lplugins_platforms_qtforandroid_$ANDROID_ARCH -ljnigraphics -landroid -lqtfreetype_$ANDROID_ARCH $QT_LIBS"
+      QT_LIBS="-Wl,--export-dynamic,--undefined=JNI_OnLoad -lplugins_platforms_qtforandroid${qt_lib_suffix} -ljnigraphics -landroid -lqtfreetype${qt_lib_suffix} $QT_LIBS"
       AC_DEFINE([QT_QPA_PLATFORM_ANDROID], [1], [Define this symbol if the qt platform is android])
     fi
   fi

depends/packages/libxcb_util.mk

@@ -8,7 +8,7 @@ $(package)_dependencies=libxcb
 define $(package)_set_vars
 $(package)_config_opts = --disable-shared --disable-devel-docs --without-doxygen
 $(package)_config_opts += --disable-dependency-tracking --enable-option-checking
-$(package)_cflags += -fPIC
+$(package)_config_opts += --with-pic
 endef
 
 define $(package)_preprocess_cmds

depends/packages/qt.mk

@@ -167,7 +167,6 @@ $(package)_config_opts_android = -xplatform android-clang
 $(package)_config_opts_android += -android-sdk $(ANDROID_SDK)
 $(package)_config_opts_android += -android-ndk $(ANDROID_NDK)
 $(package)_config_opts_android += -android-ndk-platform android-$(ANDROID_API_LEVEL)
-$(package)_config_opts_android += -device-option CROSS_COMPILE="$(host)-"
 $(package)_config_opts_android += -egl
 $(package)_config_opts_android += -qpa xcb
 $(package)_config_opts_android += -no-dbus