HasLBNEntrySourceTypeCapability: Fix it

We have a test LabnotebookUpgradeDoesNotModifyDefaultWaves which checks
that the labnotebook waves are not changed with the upgrade procedure when
they have cleared wave notes.

This test now fails as HasLBNEntrySourceTypeCapability returns 0 for a
values wave with only NaNs. But in this case it does support the entry
source type capability.

So let's fix it.

Author: t-b

Packages/MIES/MIES_MiesUtilities_Logbook.ipf

@@ -1719,15 +1719,11 @@ Function HasLBNEntrySourceTypeCapability(WAVE values)
 		return 0
 	endif
 
-	if(!DimSize(values, ROWS))
+	// wave with no rows or only NaNs
+	if(!DimSize(values, ROWS) || !HasOneValidEntry(values))
 		return 1
 	endif
 
-	if(IsNumericWave(values))
-		WaveStats/Q/M=1/RMD=[][entryCol][] values
-		return !IsNaN(V_max)
-	endif
-
 	Duplicate/FREE/RMD=[][entryCol][] values, entrySourceTypeValues
 	return HasOneValidEntry(entrySourceTypeValues)
 End