Introduce the good practise of using [] around output messages.

ext/ext_skel

@@ -123,7 +123,7 @@ if test "\$PHP_$EXTNAME" != "no"; then
   dnl if test -r \$PHP_$EXTNAME/$SEARCH_FOR; then # path given as parameter
   dnl   ${EXTNAME}_DIR=\$PHP_$EXTNAME
   dnl else # search default path list
-  dnl   AC_MSG_CHECKING(for $extname files in default path)
+  dnl   AC_MSG_CHECKING([for $extname files in default path])
   dnl   for i in \$SEARCH_PATH ; do
   dnl     if test -r \$i/\$SEARCH_FOR; then
   dnl       ${EXTNAME}_DIR=\$i
@@ -133,8 +133,8 @@ if test "\$PHP_$EXTNAME" != "no"; then
   dnl fi
   dnl
   dnl if test -z "\$${EXTNAME}_DIR"; then
-  dnl   AC_MSG_RESULT(not found)
-  dnl   AC_MSG_ERROR(Please reinstall the $extname distribution)
+  dnl   AC_MSG_RESULT([not found])
+  dnl   AC_MSG_ERROR([Please reinstall the $extname distribution])
   dnl fi
 
   dnl # --with-$extname -> add include path
@@ -146,7 +146,7 @@ if test "\$PHP_$EXTNAME" != "no"; then
   dnl old_LIBS=\$LIBS
   dnl LIBS="\$LIBS -L\$${EXTNAME}_DIR/lib -lm -ldl"
   dnl AC_CHECK_LIB(\$LIBNAME, \$LIBSYMBOL, [AC_DEFINE(HAVE_${EXTNAME}LIB,1,[ ])],
-	dnl			[AC_MSG_ERROR(wrong $extname lib version or lib not found)])
+	dnl			[AC_MSG_ERROR([wrong $extname lib version or lib not found])])
   dnl LIBS=\$old_LIBS
   dnl
   dnl PHP_SUBST(${EXTNAME}_SHARED_LIBADD)