Description of problem:
I noticed the flex-2.5.4a-gcc31.patch adds the line "using namespace
std" at the top of the skeleton file.  This causes a ambiguity if the
*.l file includes syntax that uses a function that could be global or
in the std namespace.
Example:
 fabs(int) could be ::fabs(float),std::fabs(double) or std::fabs(long
double)

Version-Release number of selected component (if applicable):
2.5.4a in Redhat 8.0 and up

How reproducible:
Use any standard function that also had a global counterpart.

Steps to Reproduce:
1. Create a *.l file with a global function that has a standard
equivilent, but leave the arguments ambiguous.
2. Compile a *.C from the *.l file with flex++
3. Try to compile the *.C file.
  
Actual results:
  You will get a compiler error that the function call is ambigious.
It trys the global function and any standard function equivilents. 

Expected results:
   Compiler should use the global 


Additional info:
   The *.l file can be written to be explicit about the function to
use, but it would be better if the flex.skel file didn't use the std
namespace over the whole file.  It would even affect header brought in
the *.l file. The istream calls in flex.skel should be scoped with
std:: instead.