Use 'int' type for backtrace() return value

The libc backtrace() API uses 'int' type for "number of pointers"
return value, and backtrace_symbols_fd() accepts this value as
argument in 'int' type, too. Using size_t would unnecessarily generate
a "-Wshorten-64-to-32" warning in Clang 19.

CRT.c

@@ -1260,8 +1260,8 @@ static void print_backtrace(void) {
 #elif defined(HAVE_EXECINFO_H)
    void* backtraceArray[256];
 
-   size_t size = backtrace(backtraceArray, ARRAYSIZE(backtraceArray));
-   backtrace_symbols_fd(backtraceArray, size, STDERR_FILENO);
+   int nptrs = backtrace(backtraceArray, ARRAYSIZE(backtraceArray));
+   backtrace_symbols_fd(backtraceArray, nptrs, STDERR_FILENO);
 #else
 #error No implementation for print_backtrace()!
 #endif