[PATCH] configure: Silence -Wincompatible-library-redeclaration warning.

[Jacek Caban]

This is noisy on clang and we can't change declarations due to long 
double type incompatibility.

Signed-off-by: Jacek Caban 
---
  configure.ac | 2 ++
  1 file changed, 2 insertions(+)