QT版本：4.8.5
由于系统原因，今天要重新编译QT，在编译PC版的qvfb的make步骤时，出现了如下错误：
.obj/release-shared/qanimationwriter.o: In function `QAnimationWriter::QAnimationWriter(QString const&, char const*)':
qanimationwriter.cpp:(.text+0xbf): undefined reference to `png_create_write_struct'
qanimationwriter.cpp:(.text+0xca): undefined reference to `png_create_info_struct'
qanimationwriter.cpp:(.text+0xe0): undefined reference to `png_set_compression_level'
qanimationwriter.cpp:(.text+0xff): undefined reference to `png_set_write_fn'
.obj/release-shared/qanimationwriter.o: In function `QAnimationWriterMNG::write(png_struct_def*, unsigned char*, unsigned int)':
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG5writeEP14png_struct_defPhj[QAnimationWriterMNG::write(png_struct_def*, unsigned char*, unsigned int)]+0xb): undefined reference to `png_get_io_ptr'
.obj/release-shared/qanimationwriter.o: In function `QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)':
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0x65): undefined reference to `png_write_chunk'
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0x78): undefined reference to `png_set_sig_bytes'
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0xda): undefined reference to `png_set_IHDR'
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0xec): undefined reference to `png_write_info'
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0x107): undefined reference to `png_set_bgr'
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0x154): undefined reference to `png_write_image'
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0x172): undefined reference to `png_write_end'
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0x184): undefined reference to `png_destroy_write_struct'
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0x1a8): undefined reference to `png_create_write_struct'
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0x1b3): undefined reference to `png_create_info_struct'
qanimationwriter.cpp:(.text._ZN19QAnimationWriterMNG12composeImageERK6QImageRK6QPoint[QAnimationWriterMNG::composeImage(QImage const&, QPoint const&)]+0x1c9): undefined re