port r17355 from 1.2: halgrind doesn't like so many calls

tools/valgrind/opencl.suppr

@@ -650,8 +650,6 @@
    fun:_dl_catch_error
    fun:_dlerror_run
    fun:dlopen@@GLIBC_2.2.5
-   obj:/usr/lib/x86_64-linux-gnu/libltdl.so.7.3.1
-   obj:/usr/lib/x86_64-linux-gnu/libltdl.so.7.3.1
-   obj:/usr/lib/x86_64-linux-gnu/libltdl.so.7.3.1
+   ...
 }