Fix typo in autogen.sh

Change-Id: I7048dc9bf49a1e83302563db269c6a89a17c6df0
Reviewed-on: https://code.wireshark.org/review/19843
Reviewed-by: Peter Wu <peter@lekensteyn.nl>

autogen.sh

@@ -26,7 +26,7 @@ DIE=true
 PROJECT="Wireshark"
 
 # If you are going to use the non-default name for automake becase your OS
-# installaion has multiple versions, you need to call both aclocal and automake
+# installation has multiple versions, you need to call both aclocal and automake
 # with that version number, as they come from the same package.
 #AM_VERSION='-1.8'