Qt 5.15.2 cross compile with different glibc and glibcxx

$ ./configure --help | grep sysroot
  -sysroot <dir> ....... Set <dir> as the target sysroot
  -gcc-sysroot ......... With -sysroot, pass --sysroot to the compiler [yes]

$ cat mkspecs/devices/linux-rasp-pi3-g++/qmake.conf
include(../common/linux_device_pre.conf)

# For modern Yocto-based sysroots that have the proper include and lib
# setup in egl.pc we will pull the necessary arguments from
# there. However, to support Raspbian and older stuff that has /opt/vc
# and possibly no pkg-config, have some static values as well:

# I consider it a bug that this is required, but our EGL config.test _requires_ it
QMAKE_RPATHLINKDIR_POST += $$[QT_SYSROOT]/opt/vc/lib

VC_LIBRARY_PATH         = /opt/vc/lib
VC_INCLUDE_PATH         = =/opt/vc/include

VC_LINK_LINE            = -L=$${VC_LIBRARY_PATH}

QMAKE_LIBDIR_OPENGL_ES2 = =$${VC_LIBRARY_PATH}
QMAKE_LIBDIR_EGL        = $$QMAKE_LIBDIR_OPENGL_ES2
QMAKE_LIBDIR_OPENVG     = $$QMAKE_LIBDIR_OPENGL_ES2

QMAKE_INCDIR_EGL        = \
                        $${VC_INCLUDE_PATH} \
                        $${VC_INCLUDE_PATH}/interface/vcos/pthreads \
                        $${VC_INCLUDE_PATH}/interface/vmcs_host/linux

QMAKE_INCDIR_OPENGL_ES2 = $${QMAKE_INCDIR_EGL}

QMAKE_LIBS_OPENGL_ES2   = $${VC_LINK_LINE} -lGLESv2

# The official opt vc EGL references GLESv2 symbols: need to link it
QMAKE_LIBS_EGL          = $${VC_LINK_LINE} -lEGL -lGLESv2

QMAKE_LIBDIR_BCM_HOST   = =$$VC_LIBRARY_PATH
QMAKE_INCDIR_BCM_HOST   = $$VC_INCLUDE_PATH
QMAKE_LIBS_BCM_HOST     = -lbcm_host

QMAKE_CFLAGS            = -march=armv8-a -mtune=cortex-a53 -mfpu=crypto-neon-fp-armv8
QMAKE_CXXFLAGS          = $$QMAKE_CFLAGS

DISTRO_OPTS            += hard-float
DISTRO_OPTS            += deb-multi-arch

EGLFS_DEVICE_INTEGRATION= eglfs_brcm

include(../common/linux_arm_device_post.conf)

load(qt_config)