title: installing jekyll gives returns error (Failed to build gem native extension.)
body: <p>I have a fresh install of fedora. I installed <code>ruby</code>, <code>ruby-devel</code> and gone through jekyll troubleshooting on their website but i still get the same error. I tried installing another gem which is <code>Sass</code>, just to make sure its not a <code>ruby</code> issue and it successfully installed.</p>
  
  <pre><code>Building native extensions.  This could take a while...
  ERROR:  Error installing jekyll:
      ERROR: Failed to build gem native extension.
  
      current directory: /usr/local/share/gems/gems/ffi-1.9.10/ext/ffi_c
  /usr/bin/ruby -r ./siteconf20160620-3296-7ascyu.rb extconf.rb
  checking for ffi.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}/lib64
      --with-make-prog
      --without-make-prog
      --srcdir=.
      --curdir
      --ruby=/usr/bin/$(RUBY_BASE_NAME)
      --with-ffi_c-dir
      --without-ffi_c-dir
      --with-ffi_c-include
      --without-ffi_c-include=${ffi_c-dir}/include
      --with-ffi_c-lib
      --without-ffi_c-lib=${ffi_c-dir}/lib64
      --with-libffi-config
      --without-libffi-config
      --with-pkg-config
      --without-pkg-config
  /usr/share/ruby/mkmf.rb:456:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
  You have to install development tools first.
      from /usr/share/ruby/mkmf.rb:587:in `try_cpp'
      from /usr/share/ruby/mkmf.rb:1060:in `block in have_header'
      from /usr/share/ruby/mkmf.rb:911:in `block in checking_for'
      from /usr/share/ruby/mkmf.rb:351:in `block (2 levels) in postpone'
      from /usr/share/ruby/mkmf.rb:321:in `open'
      from /usr/share/ruby/mkmf.rb:351:in `block in postpone'
      from /usr/share/ruby/mkmf.rb:321:in `open'
      from /usr/share/ruby/mkmf.rb:347:in `postpone'
      from /usr/share/ruby/mkmf.rb:910:in `checking_for'
      from /usr/share/ruby/mkmf.rb:1059:in `have_header'
      from extconf.rb:16:in `&lt;main&gt;'
  
  To see why this extension failed to compile, please check the mkmf.log which can be found here:
  
    /usr/local/lib64/gems/ruby/ffi-1.9.10/mkmf.log
  
  extconf failed, exit code 1
  
  Gem files will remain installed in /usr/local/share/gems/gems/ffi-1.9.10 for inspection.
  Results logged to /usr/local/lib64/gems/ruby/ffi-1.9.10/gem_make.out
  </code></pre>
  
  <p>info from <code>mkmf.log</code>:</p>
  
  <pre><code>package configuration for libffi is not found
  "gcc -o conftest -I/usr/include -I/usr/include/ruby/backward -I/usr/include -I.    -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -mtune=generic -fPIC conftest.c  -L. -L/usr/lib64 -L. -Wl,-z,relro -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -fstack-protector -rdynamic -Wl,-export-dynamic  -m64   -lruby  -lpthread -ldl -lcrypt -lm   -lc"
  checked program was:
  /* begin */
  1: #include "ruby.h"
  2: 
  3: int main(int argc, char **argv)
  4: {
  5:   return 0;
  6: }
  /* end */
  </code></pre>
  
  <p>PS: I have <code>ruby 2.2.5p319 (2016-04-26 revision 54774) [x86_64-linux]</code>
  and <code>gem 2.6.4</code> and <code>ruby-devel-2.2.5-48.fc23.x86_64</code></p>