Clarify setStackSize error message

Show the actual attempted stack size value (capped at hard limit)
separately from the desired value, making it clearer what's happening
when the hard limit is lower than requested.

Author: roberth

src/libutil/current-process.cc

@@ -65,13 +65,15 @@ void setStackSize(size_t stackSize)
     struct rlimit limit;
     if (getrlimit(RLIMIT_STACK, &limit) == 0 && static_cast<size_t>(limit.rlim_cur) < stackSize) {
         savedStackSize = limit.rlim_cur;
-        limit.rlim_cur = std::min(static_cast<rlim_t>(stackSize), limit.rlim_max);
+        auto requestedSize = std::min(static_cast<rlim_t>(stackSize), limit.rlim_max);
+        limit.rlim_cur = requestedSize;
         if (setrlimit(RLIMIT_STACK, &limit) != 0) {
             logger->log(
                 lvlError,
                 HintFmt(
-                    "Failed to increase stack size from %1% to %2% (maximum allowed stack size: %3%): %4%",
+                    "Failed to increase stack size from %1% to %2% (desired: %3%, maximum allowed: %4%): %5%",
                     savedStackSize,
+                    requestedSize,
                     stackSize,
                     limit.rlim_max,
                     std::strerror(errno))