title: Gcc error when installing psycopg2 into a virtualenv (Lubuntu 12.04, python 2.7)
body: <p>I'm trying to install psycopg2 into a virtualenv using pip but there seems to be some kind of gcc error that I can't get my head around. I've installed python-dev and libpq-dev as suggested by some other questions.</p>
  
  <pre><code>pip install psycopg2
  Downloading/unpacking psycopg2
    Running setup.py egg_info for package psycopg2
  
      no previously-included directories found matching 'doc/src/_build'
  Installing collected packages: psycopg2
    Running setup.py install for psycopg2
      building 'psycopg2._psycopg' extension
      gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION="2.4.5 (dt dec pq3 ext)" -DPG_VERSION_HEX=0x090104 -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -I/usr/include/python2.7 -I. -I/usr/include/postgresql -I/usr/include/postgresql/9.1/server -c psycopg/psycopgmodule.c -o build/temp.linux-i686-2.7/psycopg/psycopgmodule.o -Wdeclaration-after-statement
      gcc: error trying to exec 'as': execvp: No such file or directory
      error: command 'gcc' failed with exit status 1
      Complete output from command /home/mdang/Dropbox/WebDev/ideas/venv/bin/python -c "import setuptools;__file__='/home/mdang/Dropbox/WebDev/ideas/venv/build/psycopg2/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --single-version-externally-managed --record /tmp/pip-SBgH20-record/install-record.txt --install-headers /home/mdang/Dropbox/WebDev/ideas/venv/include/site/python2.7:
      running install
  
  running build
  
  running build_py
  
  running build_ext
  
  building 'psycopg2._psycopg' extension
  
  gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION="2.4.5 (dt dec pq3 ext)" -DPG_VERSION_HEX=0x090104 -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -I/usr/include/python2.7 -I. -I/usr/include/postgresql -I/usr/include/postgresql/9.1/server -c psycopg/psycopgmodule.c -o build/temp.linux-i686-2.7/psycopg/psycopgmodule.o -Wdeclaration-after-statement
  
  gcc: error trying to exec 'as': execvp: No such file or directory
  
  error: command 'gcc' failed with exit status 1
  
  ----------------------------------------
  Command /home/mdang/Dropbox/WebDev/ideas/venv/bin/python -c "import setuptools;__file__='/home/mdang/Dropbox/WebDev/ideas/venv/build/psycopg2/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --single-version-externally-managed --record /tmp/pip-SBgH20-record/install-record.txt --install-headers /home/mdang/Dropbox/WebDev/ideas/venv/include/site/python2.7 failed with error code 1 in /home/mdang/Dropbox/WebDev/ideas/venv/build/psycopg2
  Storing complete log in /home/mdang/.pip/pip.log
  </code></pre>