Fix remaining static analysis warnings

Fix or suppress the remaining warnings generated by static analysis.
This is a necessary step before we can incorporate static analysis into
CI. Where possible, I've preferred to modify the code itself instead of
just disabling the warning with a magic comment, so that if we decide to
use different static analysis tools in the future we will be covered
against them raising similar warnings.

src/jemalloc_cpp.cpp

@@ -1,5 +1,6 @@
 #include <mutex>
 #include <new>
+// NOLINTBEGIN(misc-use-anonymous-namespace)
 
 #define JEMALLOC_CPP_CPP_
 #ifdef __cplusplus
@@ -258,3 +259,4 @@ operator delete[](void* ptr, std::size_t size, std::align_val_t alignment) noexc
 }
 
 #endif  // __cpp_aligned_new
+// NOLINTEND(misc-use-anonymous-namespace)