Detect TOPCOM package on Arch Linux

It prepends "topcom-" to just some of the binaries.  This means we
need to check two binaries (one with the prefix and one without) to
distinguish the Arch package from the Debian one (which prepends
"topcom-" to everything).

M2/Macaulay2/packages/Topcom.m2

@@ -77,10 +77,12 @@ topcomPoints Matrix := opts -> (A) -> (
 callTopcom = method()
 callTopcom(String, List) := (command, inputs) -> (
     if topcomProgram === null then
-	topcomProgram = findProgram("topcom","cube 3", Prefix => {
+	topcomProgram = findProgram("topcom", {"cube 3", "B_A 3"}, Prefix => {
 	    (".*", "topcom-"), -- debian
 	    ("^(cross|cube|cyclic|hypersimplex|lattice)$", "TOPCOM-"), --fedora
-	    ("^cube$", "topcom_")}); --gentoo
+	    ("^cube$", "topcom_"), --gentoo
+	    ("^(binomial|cross|cube|cyclic|lattice)$", "topcom-") --arch
+	    });
     filename := temporaryFileName();
     infile := filename|".in";
     -- now create the output file