tdf#42949 Fix IWYU warnings in salhelper/

Found with bin/find-unneeded-includes
Only removal proposals are dealt with here
and only for files that are actually compiling

Change-Id: I70357eade9552984fdb3b7590f1e8237a02a7d1d
Reviewed-on: https://gerrit.libreoffice.org/65650
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>

include/salhelper/condition.hxx

@@ -29,9 +29,6 @@ namespace osl { class Mutex; }
 
 namespace salhelper
 {
-    class ConditionModifier;
-    class ConditionWaiter;
-
 
     class SALHELPER_DLLPUBLIC Condition
     {

salhelper/IwyuFilter_salhelper.yaml

@@ -0,0 +1,2 @@
+---
+assumeFilename: salhelper/source/dynload.cxx

salhelper/qa/test_api.cxx

@@ -30,14 +30,6 @@
 #include <cppunit/plugin/TestPlugIn.h>
 #include <memory>
 
-namespace salhelper {
-    class Condition;
-    class ConditionModifier;
-    class ConditionWaiter;
-    class ORealDynamicLoader;
-    class SimpleReferenceObject;
-}
-
 namespace {
 
 std::type_info const & getConditionTypeInfo()

salhelper/source/dynload.cxx

@@ -18,7 +18,6 @@
  */
 
 #include <salhelper/dynload.hxx>
-#include <rtl/ustrbuf.hxx>
 
 namespace salhelper
 {

salhelper/source/timer.cxx

@@ -17,7 +17,6 @@
  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  */
 #include <salhelper/timer.hxx>
-#include <salhelper/simplereferenceobject.hxx>
 
 #include <osl/thread.hxx>
 #include <osl/conditn.hxx>