Update README.org

Add pkg-config to brew install command to avoid this error:
checking for PostgreSQL libraries... yes
./configure: line 4064: syntax error near unexpected token `LIBPQXX,'
./configure: line 4064: `PKG_CHECK_MODULES(LIBPQXX, libpqxx >= 4.0)'

Author: gregrahn

README.org

@@ -43,7 +43,7 @@ optional:
 
 In order to build on Mac OSX, assuming you use Homebrew, run the following
 
-: brew install libpqxx automake libtool autoconf autoconf-archive
+: brew install libpqxx automake libtool autoconf autoconf-archive pkg-config
 : cd sqlsmith
 : autoreconf -i # Not needed when building from a release tarball
 : ./configure