Add casts to fix type conversion warnings
Add casts to fix type conversion warnings

In particular this warning:

	../../groups/bsl/bslstl/bslstl_hashtable.cpp: In static member function 'static size_t BloombergLP::bslstl::HashTable_ImpDetails::growBucketsForLoadFactor(size_t*, size_t, size_t, double)':
	../../groups/bsl/bslstl/bslstl_hashtable.cpp:79:28: error: conversion to 'double' from 'size_t {aka long unsigned int}' may alter its value [-Werror=conversion]
		 if (minElements <= newCapacity) {
				    ^~~~~~~~~~~
	cc1plus: all warnings being treated as errors

bloomberg/bde,che2/bde,bloomberg/bde,bloomberg/bde,che2/bde,bloomberg/bde,che2/bde,bloomberg/bde,che2/bde