include absolute path to library

$ toolchain/arm-histbv310-linux/bin/arm-histbv310-linux-objdump -x build-arm-hi3798mv100/qtbase-5.12.2/plugins/imageformats/libqjpeg.so | less
build-arm-hi3798mv100/qtbase-5.12.2/plugins/imageformats/libqjpeg.so:     file format elf32-littlearm
build-arm-hi3798mv100/qtbase-5.12.2/plugins/imageformats/libqjpeg.so
architecture: arm, flags 0x00000150:
HAS_SYMS, DYNAMIC, D_PAGED
start address 0x00002ef0

Program Header:
    LOAD off    0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**16
         filesz 0x00007f4c memsz 0x00007f4c flags r-x
    LOAD off    0x00008000 vaddr 0x00018000 paddr 0x00018000 align 2**16
         filesz 0x00000434 memsz 0x00000444 flags rw-
 DYNAMIC off    0x000080d0 vaddr 0x000180d0 paddr 0x000180d0 align 2**2
         filesz 0x00000138 memsz 0x00000138 flags rw-
   STACK off    0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**4
         filesz 0x00000000 memsz 0x00000000 flags rw-

Dynamic Section:
  NEEDED               libhi_common.so
  NEEDED               libpthread.so.0
  NEEDED               libQt5Gui.so.5
  NEEDED               libQt5Core.so.5
  NEEDED               /tmp/firmware/staging_board/usr/lib/libjpeg.so
  NEEDED               libstdc++.so.6
  NEEDED               libm.so.6
  NEEDED               libgcc_s.so.1
  NEEDED               libc.so.6
  RUNPATH              $ORIGIN/../../lib
  INIT                 0x000028fc
..............

.............
> make[1]: Entering directory '/tmp/firmware/build-arm-hi3798mv100/qtbase-5.12.2/config.tests/libjpeg'
> arm-histbv310-linux-g++ -c -pipe -mcpu=cortex-a7 -mfloat-abi=softfp -mfpu=neon-vfpv4 -O2 -std=gnu++11 -w -fPIC  -I. -I/tmp/firmware/staging_board/usr/include -I/tmp/firmware/_dependencies/qtbase/mkspecs/devices/linux-arm-hisilicon-hi3798mv100-g++ -o main.o main.cpp
> arm-histbv310-linux-g++ -lhi_common -lpthread -Wl,-O1 -o libjpeg main.o   -L/tmp/firmware/staging_board/usr/lib /tmp/firmware/staging_board/usr/lib/libjpeg.so   
> make[1]: Leaving directory '/tmp/firmware/build-arm-hi3798mv100/qtbase-5.12.2/config.tests/libjpeg
........

$ git diff
diff --git a/src/plugins/imageformats/jpeg/jpeg.pro b/src/plugins/imageformats/jpeg/jpeg.pro
index 89476e62f5..06bd7f3dbd 100644
--- a/src/plugins/imageformats/jpeg/jpeg.pro
+++ b/src/plugins/imageformats/jpeg/jpeg.pro
@@ -6,7 +6,8 @@ SOURCES += main.cpp qjpeghandler.cpp
 HEADERS += main.h qjpeghandler_p.h
 
 qtConfig(system-jpeg) {
-    QMAKE_USE += libjpeg
+#    QMAKE_USE += libjpeg
+       LIBS += -ljpeg
 } else {
     include($$PWD/../../../3rdparty/libjpeg.pri)
 }