Use temporary baseline of unreleased CDT 11.3.1

This is to workaround the missing BREE in CDT 11.3.0, see
#551 for details

Part of #551

pom.xml

@@ -44,8 +44,8 @@
 		<tycho.scmUrl>scm:git:https://github.com/eclipse-cdt/cdt</tycho.scmUrl>
 		<!-- Some old tests, like CDescriptorOldTests, fail due to reflection access. Therefore we add-opens to make that pass -->
 		<base.test.vmargs>-Xms256m -Xmx512m -ea --add-opens=java.xml/com.sun.org.apache.xerces.internal.dom=ALL-UNNAMED</base.test.vmargs>
-		<comparator.repo>https://download.eclipse.org/tools/cdt/releases/latest/</comparator.repo>
-		<api-baseline.repo>https://download.eclipse.org/tools/cdt/releases/latest/</api-baseline.repo>
+		<comparator.repo>https://download.eclipse.org/tools/cdt/releases/11.3/cdt-11.3.1/</comparator.repo>
+		<api-baseline.repo>https://download.eclipse.org/tools/cdt/releases/11.3/cdt-11.3.1/</api-baseline.repo>
 		<api-baseline.repo.simrel>https://download.eclipse.org/releases/latest/</api-baseline.repo.simrel>
 		<!-- these parameters are to control baseline replace and compare. On a local build you want
 		     to avoid baseline replace and compare, especially if you have different versions of Java than

releng/org.eclipse.cdt.target/cdt-baseline.target

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <?pde version="3.8"?>
-<target name="cdt-baseline" sequenceNumber="34">
+<target name="cdt-baseline" sequenceNumber="35">
   <locations>
     <location includeAllPlatforms="true" includeConfigurePhase="true" includeMode="slicer" includeSource="false" type="InstallableUnit">
-      <repository location="https://download.eclipse.org/tools/cdt/releases/latest"/>
+      <repository location="https://download.eclipse.org/tools/cdt/releases/11.3/cdt-11.3.1/"/>
       <unit id="org.eclipse.cdt.autotools.feature.group" version="0.0.0"/>
       <unit id="org.eclipse.cdt.build.crossgcc.feature.group" version="0.0.0"/>
       <unit id="org.eclipse.cdt.cmake.feature.group" version="0.0.0"/>