Use CHAR_BIT for C++98 compatibility

Author: Alexander Grund

src/libPMacc/include/algorithms/reverseBits.hpp

@@ -25,7 +25,7 @@
 
 #include "static_assert.hpp"
 #include <boost/type_traits.hpp>
-#include <limits>
+#include <climits>
 
 namespace PMacc {
 
@@ -48,7 +48,7 @@ reverseBits(T value)
     /* init with value (to get LSB) */
     T result = value;
     /* extra shift needed at end */
-    int s = std::numeric_limits<T>::digits - 1;
+    int s = sizeof(T) * CHAR_BIT - 1;
     for (value >>= 1; value; value >>= 1)
     {
         result <<= 1;

src/libPMacc/include/mpi/SeedPerRank.hpp

@@ -68,7 +68,7 @@ namespace mpi
             /* localSeed often contains a counted number, so we rotate it by some bits to not "destroy"
              * the counted rank that is already there. Also it is not reversed to get a different pattern
              */
-            localSeed = (localSeed << 16) | (localSeed >> (std::numeric_limits<uint32_t>::digits - 16));
+            localSeed = (localSeed << 16) | (localSeed >> (sizeof(uint32_t) * CHAR_BIT - 16));
             globalUniqueSeed ^= localSeed;
             /* For any globally constant localSeed globalUniqueSeed is now guaranteed
              * to be globally unique