[flang] Fixed compiler build on glibc 2.17 systems after 3149c93. (llvm#84873)

Author: vzakhari

flang/include/flang/Evaluate/integer.h

@@ -27,6 +27,10 @@
 #include <string>
 #include <type_traits>
 
+// Some environments, viz. glibc 2.17, allow the macro HUGE
+// to leak out of <math.h>.
+#undef HUGE
+
 namespace Fortran::evaluate::value {
 
 // Implements an integer as an assembly of smaller host integer parts

flang/include/flang/Evaluate/real.h

@@ -18,6 +18,10 @@
 #include <limits>
 #include <string>
 
+// Some environments, viz. glibc 2.17, allow the macro HUGE
+// to leak out of <math.h>.
+#undef HUGE
+
 namespace llvm {
 class raw_ostream;
 }

flang/lib/Evaluate/fold-implementation.h

@@ -39,6 +39,10 @@
 #include <type_traits>
 #include <variant>
 
+// Some environments, viz. glibc 2.17, allow the macro HUGE
+// to leak out of <math.h>.
+#undef HUGE
+
 namespace Fortran::evaluate {
 
 // Utilities