DAOS-19102 control: strip trailing whitespace in get_build_flags comment

Signed-off-by: Michael MacDonald <github@macdonald.cx>

Author: mjmac

src/control/SConscript

@@ -56,7 +56,7 @@ def get_build_flags(benv):
     flags = '-gcflags "all=-N -l"'
     # Valgrind variant: instrument the Go runtime for Memcheck and leave the
     # race detector off because it does not stack with memcheck.
-    # 
+    #
     if benv.d_is_valgrind_build():
         return flags
     # enable AddressSanitizer to detect memory safety issues at runtime