Bump to v2.1.2: Make PProf.Allocs profiling support backported julia versions

Use an `isdefined()` check instead of a `VERSION` check: #52

Author: NHDaly

Project.toml

@@ -1,7 +1,7 @@
 name = "PProf"
 uuid = "e4faabce-9ead-11e9-39d9-4379958e3056"
 authors = ["Valentin Churavy <v.churavy@gmail.com>", "Nathan Daly <nhdaly@gmail.com>"]
-version = "2.1.1"
+version = "2.1.2"
 
 [deps]
 AbstractTrees = "1520ce14-60c1-5f80-bbc7-55ef81b5835c"