title: ARM toolchain looks in the wrong directory for libraries
body: <p>For my project I need to compile Qt 5.9.1 for a generic ARM device. I've set up linaro's toolchain. But Qt configure halts at this:</p>
  
  <blockquote>
    <p>/usr/bin/arm-linux-gnueabihf-g++ -mfloat-abi=hard --sysroot=/mnt/elvees-rootfs/ -Wl,-O1 -fuse-ld=gold -o verifyspec verifyspec.o<br>
    /usr/bin/arm-linux-gnueabihf-ld.gold: error: /lib/libc.so.6: incompatible target
    /usr/bin/arm-linux-gnueabihf-ld.gold: error: cannot open /lib/ld-linux-armhf.so.3: No such file or directory
    /usr/bin/arm-linux-gnueabihf-ld.gold: error: /lib/libc_nonshared.a(elf-init.oS): incompatible target
    ../sysdeps/arm/start.S:124: error: undefined reference to '__libc_start_main'
    ../sysdeps/arm/start.S:128: error: undefined reference to 'abort'
    ../sysdeps/arm/start.S:113: error: undefined reference to '__libc_csu_fini'
    ../sysdeps/arm/start.S:120: error: undefined reference to '__libc_csu_init'
    collect2: error: ld returned 1 exit status</p>
  </blockquote>
  
  <p>From the looks of it, arm-linux-gnueabihf-g++ looks for libs in host's /lib/ directory, instead of the sysroot's. Any reason for such a behavior and how to fix it? My best bet is the broken symlinks in the mounted sysroot, but I've manualy changed the "libc.so.6" one, and the output is still the same.
  To clarify, host and target are running Arch.</p>
  
  <p><strong>Edit</strong></p>
  
  <p>By request, here is my qmake.conf (that generates mkspec):</p>
  
  <pre><code>include(../common/linux_device_pre.conf)
  
  ELVEES_CFLAGS             = -march=armv7-a -mtune=cortex-a9 -mfpu=neon-fp16 -DLINUX=1
  QMAKE_CFLAGS           += $$ELVEES_CFLAGS
  QMAKE_CXXFLAGS         += $$ELVEES_CFLAGS 
  
  DISTRO_OPTS += hard-float
  
  QT_QPA_DEFAULT_PLATFORM = eglfs
  
  include(../common/linux_arm_device_post.conf)
  
  QMAKE_INCDIR_EGL        = /mnt/elvees-rootfs/usr/include/EGL
  QMAKE_LIBDIR_EGL        = /mnt/elvees-rootfs/usr/lib
  QMAKE_INCDIR_OPENGL_ES2 = /mnt/elvees-rootfs/include/GLES2
  QMAKE_LIBDIR_OPENGL_ES2 = /mnt/elvees-rootfs/usr/lib
  
  QMAKE_LIBS_EGL          = -lEGL
  QMAKE_LIBS_OPENGL_ES2   = -lGLESv2 $${QMAKE_LIBS_EGL}
  
  load(qt_config)
  </code></pre>
  
  <p>And these are the qt_config options:</p>
  
  <pre><code>./configure \
  -opengl es2 \
  -device arch-elvees-g++ \
  -device-option CROSS_COMPILE=/usr/bin/arm-linux-gnueabihf- \
  -sysroot /mnt/elvees-rootfs/ \
  -opensource \
  -confirm-license \
  -optimized-qmake \
  -release \
  -make libs \
  -prefix /opt/qt-elvees\
  -no-pch \
  -nomake examples \
  -nomake tests \
  -no-xcb \
  -eglfs \
  -v 
  </code></pre>