tools/m4: fix codespell issues

gl/m4/libtool.m4

@@ -604,7 +604,7 @@ m4_popdef([AS_MESSAGE_LOG_FD])])])# _LT_GENERATED_FILE_INIT
 # LT_OUTPUT
 # ---------
 # This macro allows early generation of the libtool script (before
-# AC_OUTPUT is called), incase it is used in configure for compilation
+# AC_OUTPUT is called), in case it is used in configure for compilation
 # tests.
 AC_DEFUN([LT_OUTPUT],
 [: ${CONFIG_LT=./config.lt}
@@ -641,7 +641,7 @@ configured by $[0], generated by m4_PACKAGE_STRING.
 
 Copyright (C) 2011 Free Software Foundation, Inc.
 This config.lt script is free software; the Free Software Foundation
-gives unlimited permision to copy, distribute and modify it."
+gives unlimited permission to copy, distribute and modify it."
 
 while test $[#] != 0
 do

gl/m4/ltsugar.m4

@@ -75,7 +75,7 @@ m4_define([lt_combine],
 
 # lt_if_append_uniq(MACRO-NAME, VARNAME, [SEPARATOR], [UNIQ], [NOT-UNIQ])
 # -----------------------------------------------------------------------
-# Iff MACRO-NAME does not yet contain VARNAME, then append it (delimited
+# If MACRO-NAME does not yet contain VARNAME, then append it (delimited
 # by SEPARATOR if supplied) and expand UNIQ, else NOT-UNIQ.
 m4_define([lt_if_append_uniq],
 [m4_ifdef([$1],

m4/np_mysqlclient.m4

@@ -65,7 +65,7 @@ AC_DEFUN([np_mysqlclient],
   fi
 ])
 
-dnl Will take $1, find last occurrance of -LDIR and add DIR to LD_RUN_PATH
+dnl Will take $1, find last occurrence of -LDIR and add DIR to LD_RUN_PATH
 AC_DEFUN([np_add_to_runpath], 
 [
   dnl Need [[ ]] so autoconf gives us just one set