所以我从源代码安装了GraphicsMagick,并再次禁用了OpenMP功能.但是,当我安装rmagick我得到以下内容：

Building native extensions.  This could take a while...
ERROR:  Error installing rmagick-2.13.1.gem:
        ERROR: Failed to build gem native extension.

        /usr/bin/ruby1.8 extconf.rb --build-opts --with-graphics-magick
checking for Ruby version >= 1.8.5... yes
checking for gcc... yes
checking for Magick-config... yes

Warning: Found a partial ImageMagick installation. Your operating system likely has some built-in ImageMagick libraries but not all of ImageMagick. This will most likely cause problems at both compile and runtime.
Found partial installation at: /usr
checking for ImageMagick version >= 6.4.9... yes
checking for HDRI disabled version of ImageMagick... yes
Package MagickCore was not found in the pkg-config search path.
Perhaps you should add the directory containing `MagickCore.pc'
to the PKG_CONFIG_PATH environment variable
No package 'MagickCore' found
Package MagickCore was not found in the pkg-config search path.
Perhaps you should add the directory containing `MagickCore.pc'
to the PKG_CONFIG_PATH environment variable
No package 'MagickCore' found
Package MagickCore was not found in the pkg-config search path.
Perhaps you should add the directory containing `MagickCore.pc'
to the PKG_CONFIG_PATH environment variable
No package 'MagickCore' found
Package MagickCore was not found in the pkg-config search path.
Perhaps you should add the directory containing `MagickCore.pc'
to the PKG_CONFIG_PATH environment variable
No package 'MagickCore' found
checking for stdint.h... yes
checking for sys/types.h... yes
checking for wand/MagickWand.h... no

Can't install RMagick 2.13.1. Can't find MagickWand.h.
*** extconf.rb Failed ***
Could not create Makefile due to some reason,probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=/usr/bin/ruby1.8

我已经试图运行：

export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig

并检查文件夹pkgconfig的内容：

freetype2.pc  GraphicsMagick.pc  GraphicsMagick++.pc  GraphicsMagickWand.pc  libpng15.pc  libpng.pc

我在这里缺少什么？