Add missing refprefixes for theorems (#8781)

Original patch by Paul Rubin

lib/layouts/theorems-ams-extended-bytype.module

@@ -404,3 +404,5 @@ Style Assumption*
 	  \addto\captions$$lang{\renewcommand{\assumptionname}{_(Assumption)}}
 	EndBabelPreamble
 End
+
+Input theorems-refprefix.inc

lib/layouts/theorems-ams-extended.module

@@ -407,3 +407,5 @@ Style Question*
 	  \addto\captions$$lang{\renewcommand{\questionname}{_(Question)}}
 	EndBabelPreamble
 End
+
+Input theorems-refprefix.inc

lib/layouts/theorems-refprefix.inc

@@ -17,3 +17,75 @@ End
 IfStyle Proposition
 	RefPrefix prop
 End
+
+IfStyle Conjecture
+	RefPrefix conj
+End
+
+IfStyle Definition
+	RefPrefix def
+End
+
+IfStyle Example
+	RefPrefix exa
+End
+
+IfStyle Problem
+	RefPrefix prob
+End
+
+IfStyle Exercise
+	RefPrefix exer
+End
+
+IfStyle Remark
+	RefPrefix rem
+End
+
+IfStyle Claim
+	RefPrefix claim
+End
+
+IfStyle Fact
+	RefPrefix fact
+End
+
+IfStyle Criterion
+	RefPrefix cri
+End
+
+IfStyle Algorithm
+	RefPrefix alg
+End
+
+IfStyle Axiom
+	RefPrefix axm
+End
+
+IfStyle Condition
+	RefPrefix cond
+End
+
+IfStyle Note
+	RefPrefix note
+End
+
+IfStyle Notation
+	RefPrefix nota
+End
+
+IfStyle Summary
+	RefPrefix sum
+End
+
+IfStyle Acknowledgement
+	RefPrefix ack
+End
+
+IfStyle Conclusion
+	RefPrefix conc
+End
+
+IfStyle Assumption
+	RefPrefix assu
+End