Fix lock guads in PipePosix.cpp (#90572)

Guard object destroyed immediately after creation without naming.

Author: dklimkin

lldb/source/Host/posix/PipePosix.cpp

@@ -108,7 +108,7 @@ Status PipePosix::CreateNew(bool child_processes_inherit) {
 }
 
 Status PipePosix::CreateNew(llvm::StringRef name, bool child_process_inherit) {
-  std::scoped_lock<std::mutex, std::mutex> (m_read_mutex, m_write_mutex);
+  std::scoped_lock<std::mutex, std::mutex> guard(m_read_mutex, m_write_mutex);
   if (CanReadUnlocked() || CanWriteUnlocked())
     return Status("Pipe is already opened");
 
@@ -146,7 +146,7 @@ Status PipePosix::CreateWithUniqueName(llvm::StringRef prefix,
 
 Status PipePosix::OpenAsReader(llvm::StringRef name,
                                bool child_process_inherit) {
-  std::scoped_lock<std::mutex, std::mutex> (m_read_mutex, m_write_mutex);
+  std::scoped_lock<std::mutex, std::mutex> guard(m_read_mutex, m_write_mutex);
 
   if (CanReadUnlocked() || CanWriteUnlocked())
     return Status("Pipe is already opened");