Add missing std::map include

irep.h provides std::map if, and only if, NAMED_SUB_IS_FORWARD_LIST is
not set.

Also cleanup include guards (pushing them to be the outermost
preprocessor directives) and indentation of includes.

Author: tautschnig

src/memory-analyzer/gdb_api.h

@@ -22,6 +22,7 @@ Author: Malte Mues <[email protected]>
 #include <algorithm>
 #include <exception>
 #include <forward_list>
+#include <map>
 
 #include <util/exception_utils.h>