Add the const parameter checker.

This complains if a non-const parameter is not modified. In the PALs,
the size parameter is modified only by some implementations, so we can
make it const in the ones where it isn't.

Author: davidchisnall

.clang-tidy

@@ -1,4 +1,4 @@
-Checks:          '-clang-analyzer-security.insecureAPI.bzero,clang-diagnostic-*,google-readability-casting,readability-else-after-return,performance-unnecessary-copy-initialization,bugprone-use-after-move,modernize-use-nullptr,modernize-redundant-void-arg,modernize-return-braced-init-list,modernize-use-default-member-init,modernize-use-equals-default,modernize-use-equals-delete,modernize-use-nodiscard,modernize-use-override,cppcoreguidelines-avoid-goto,misc-unconventional-assign-operator,cppcoreguidelines-narrowing-conversions,bugprone-assert-side-effect,bugprone-bool-pointer-implicit-conversion,bugprone-copy-constructor-init,bugprone-forward-declaration-namespace,bugprone-forwarding-reference-overload,bugprone-macro-parentheses,bugprone-macro-repeated-side-effects,bugprone-move-forwarding-reference,bugprone-misplaced-widening-cast,bugprone-swapped-arguments,bugprone-undelegated-constructor,bugprone-unused-raii,cert-dcl21-cpp,llvm-namespace-comment,misc-static-assert,misc-redundant-expression,modernize-loop-convert,modernize-use-using'
+Checks:          '-clang-analyzer-security.insecureAPI.bzero,clang-diagnostic-*,google-readability-casting,readability-else-after-return,performance-unnecessary-copy-initialization,bugprone-use-after-move,modernize-use-nullptr,modernize-redundant-void-arg,modernize-return-braced-init-list,modernize-use-default-member-init,modernize-use-equals-default,modernize-use-equals-delete,modernize-use-nodiscard,modernize-use-override,cppcoreguidelines-avoid-goto,misc-unconventional-assign-operator,cppcoreguidelines-narrowing-conversions,bugprone-assert-side-effect,bugprone-bool-pointer-implicit-conversion,bugprone-copy-constructor-init,bugprone-forward-declaration-namespace,bugprone-forwarding-reference-overload,bugprone-macro-parentheses,bugprone-macro-repeated-side-effects,bugprone-move-forwarding-reference,bugprone-misplaced-widening-cast,bugprone-swapped-arguments,bugprone-undelegated-constructor,bugprone-unused-raii,cert-dcl21-cpp,llvm-namespace-comment,misc-static-assert,misc-redundant-expression,modernize-loop-convert,modernize-use-using,performance-noexcept-move-constructor,readability-non-const-parameter'
 # It would be nice to enable:
 # - readability-magic-numbers
 # - modernize-avoid-c-arrays

src/pal/pal_freebsd.h

@@ -64,7 +64,7 @@ namespace snmalloc
     }
 
     template<bool committed>
-    void* reserve(size_t* size, size_t align) noexcept
+    void* reserve(const size_t* size, size_t align) noexcept
     {
       size_t request = *size;
       // Alignment must be a power of 2.