Better wording and comments for klib compatibility code

compiler/util-klib/src/org/jetbrains/kotlin/library/KotlinAbiVersion.kt

@@ -36,6 +36,8 @@ data class KotlinAbiVersion(val major: Int, val minor: Int, val patch: Int) {
     fun isCompatible(): Boolean = isCompatibleTo(CURRENT)
 
     private fun isCompatibleTo(ourVersion: KotlinAbiVersion): Boolean {
+        // Versions before 1.4.1 were the active development phase.
+        // Starting with 1.4.1 we are trying to maintain some backward compatibility.
         return if (this.isAtLeast(1, 4, 1))
             major == ourVersion.major && minor <= ourVersion.minor
         else

compiler/util-klib/src/org/jetbrains/kotlin/library/SearchPathResolver.kt

@@ -225,7 +225,7 @@ abstract class KotlinLibraryProperResolverWithAttributes<L : KotlinLibrary>(
         val candidateLibraryVersion = candidate.versions.libraryVersion
 
         if (candidateAbiVersion?.isCompatible() != true) {
-            logger.warning("skipping $candidatePath. Incompatible abi version. Expected '${KotlinAbiVersion.CURRENT}', found '${candidateAbiVersion}'. The library produced by ${candidateCompilerVersion} compiler")
+            logger.warning("skipping $candidatePath. Incompatible abi version. The current default is '${KotlinAbiVersion.CURRENT}', found '${candidateAbiVersion}'. The library produced by ${candidateCompilerVersion} compiler")
             return false
         }