isinf(3) is a C99 feature, but PostgreSQL is not able to cope a global -std=c99 option. But it has an internal fallback for isinf(3), so force it to use this one

postgresql/postgresql.spec

@@ -45,7 +45,7 @@ Class:        BASE
 Group:        Database
 License:      GPL
 Version:      %{V_postgresql}
-Release:      20050906
+Release:      20050927
 
 #   package options
 %option       with_server    yes
@@ -201,6 +201,8 @@ AutoReqProv:  no
     rm -rf $RPM_BUILD_ROOT
 
     #   configure package
+    ( echo "ac_cv_func_isinf=no"
+    ) >config.cache
     CC="%{l_cc}" \
 %if "%{with_slony1}" == "yes"
     CFLAGS="%{l_cflags -O} -pthread" \