Make "pal_supports" not a function

But rather a template vardecl, as per C++14

src/mem/alloc.h

@@ -1120,7 +1120,7 @@ namespace snmalloc
           else if constexpr (decommit_strategy == DecommitSuperLazy)
           {
             static_assert(
-              pal_supports<LowMemoryNotification, MemoryProvider>(),
+              pal_supports<LowMemoryNotification, MemoryProvider>,
               "A lazy decommit strategy cannot be implemented on platforms "
               "without low memory notifications");
           }

src/mem/chunkmap.h

@@ -47,7 +47,7 @@ namespace snmalloc
 // Use flat map is under a single node.
 #  define SNMALLOC_MAX_FLATPAGEMAP_SIZE PAGEMAP_NODE_SIZE
 #endif
-  static constexpr bool USE_FLATPAGEMAP = pal_supports<LazyCommit>() ||
+  static constexpr bool USE_FLATPAGEMAP = pal_supports<LazyCommit> ||
     (SNMALLOC_MAX_FLATPAGEMAP_SIZE >=
      sizeof(FlatPagemap<SUPERSLAB_BITS, uint8_t>));
 

src/mem/largealloc.h

@@ -190,7 +190,7 @@ namespace snmalloc
     SNMALLOC_FAST_PATH
     uint64_t low_memory_epoch()
     {
-      if constexpr (pal_supports<LowMemoryNotification, PAL>())
+      if constexpr (pal_supports<LowMemoryNotification, PAL>)
       {
         return PAL::low_memory_epoch();
       }
@@ -203,7 +203,7 @@ namespace snmalloc
     template<bool committed>
     void* reserve(size_t* size, size_t align) noexcept
     {
-      if constexpr (pal_supports<AlignedAllocation, PAL>())
+      if constexpr (pal_supports<AlignedAllocation, PAL>)
       {
         return PAL::template reserve<committed>(size, align);
       }

src/pal/pal.h

@@ -61,8 +61,5 @@ namespace snmalloc
    * Query whether the PAL supports a specific feature.
    */
   template<PalFeatures F, typename PAL = Pal>
-  constexpr static bool pal_supports()
-  {
-    return (PAL::pal_features & F) == F;
-  }
+  constexpr static bool pal_supports = (PAL::pal_features & F) == F;
 } // namespace snmalloc