vim-patch:9.1.0796: filetype: libtool files are not recognized

Problem:  filetype: libtool files are not recognized
Solution: detect '*.{lo,la,lai}' as sh filetype
          (Wu, Zhenyu)

closes: vim/vim#15751

bfe568d8c4

Co-authored-by: Wu, Zhenyu <wuzhenyu@ustc.edu>

runtime/lua/vim/filetype.lua

@@ -1068,6 +1068,9 @@ local extension = {
   envrc = detect.sh,
   ksh = detect.ksh,
   sh = detect.sh,
+  lo = 'sh',
+  la = 'sh',
+  lai = 'sh',
   mdd = 'sh',
   sieve = 'sieve',
   siv = 'sieve',