[lmi] compilation problem in round_to_test.cpp

[Vadim Zeitlin]

 Sorry for the avalanche of problems but they just seem to keep coming
tonight: this time there is a problem with the (re)definition of
e_ieee754_rounding enum in round_to_test.cpp -- g++ (correctly) complains
that it is already defined in fenv_lmi_x86.hpp.

 I think the reason this problem isn't seen under Windows must be that
__STDC_IEC_559__ is not defined by the version of mingw32 used there as
otherwise I don't know how could it compile. But in any case this change
is at least consistent with fenv_lmi.hpp and does fix compilation of the
test for me:

--- round_to_test.cpp   2008-03-31 02:22:24 +0000
+++ round_to_test.cpp   2008-06-01 23:20:41 +0000
@@ -37,7 +37,9 @@
 #include <iostream>
 #include <ostream>

-#ifdef __STDC_IEC_559__
+#if defined LMI_X86
+    // "fenv_lmi_x86.hpp" provides the necessary values.
+#elif defined __STDC_IEC_559__
     // In case the C++ compiler offers C99 fesetround(), assume that
     // it defines __STDC_IEC_559__, but doesn't support
     //   #pragma STDC FENV_ACCESS ON
@@ -49,8 +51,6 @@
         ,fe_upward     = FE_UPWARD
         ,fe_towardzero = FE_TOWARDZERO
         };
-#elif defined LMI_X86
-    // "fenv_lmi_x86.hpp" provides the necessary values.
 #else  // No known way to set rounding style.
 #   error No known way to set rounding style.
 #endif // No known way to set rounding style.

(although it's not totally clear from the diff, this patch simply changes
the order of __STDC_IEC_559__ and LMI_X86 checks).

 As before, please let me know if you want me to apply this directly or if
you prefer to take care of this yourself.

 Thanks,
VZ