[lldb] try to fix build on linux after fc6b725

Tries to fix:

    ../../lldb/source/Breakpoint/WatchpointResource.cpp:59:12:
    error: no member named 'find' in namespace 'std'; did you mean 'fill'?
          std::find(m_constituents.begin(), m_constituents.end(), wp_sp);
          ~~~~~^~~~
               fill

(cherry picked from commit a6c62bf)

Author: nico

lldb/source/Breakpoint/WatchpointResource.cpp

@@ -10,6 +10,8 @@
 
 #include "lldb/Breakpoint/WatchpointResource.h"
 
+#include <algorithm>
+
 using namespace lldb;
 using namespace lldb_private;