Fix minor Autoconf coding style

This fixes two minor Autoconf coding styles. Double quotes in arguments
don't need to be escaped. This removes warning given by autoreconf:
- warning: back quotes and double quotes must not be escaped in...

Author: petk

ext/pdo_odbc/config.m4

@@ -11,7 +11,7 @@ define([PDO_ODBC_HELP_TEXT],[[
 			    --with-pdo-odbc=unixODBC
 
 			  will check for unixODBC under /usr/local. You may attempt
-			  to use an otherwise unsupported driver using the \"generic\"
+			  to use an otherwise unsupported driver using the 'generic'
 			  flavour.  The syntax for generic ODBC support is:
 
 			    --with-pdo-odbc=generic,dir,libname,ldflags,cflags

ext/standard/config.m4

@@ -409,7 +409,7 @@ dnl Check for argon2
 dnl
 PHP_ARG_WITH(password-argon2, for Argon2 support,
 [  --with-password-argon2[=DIR]
-                          Include Argon2 support in password_*. DIR is the Argon2 shared library path]])
+                          Include Argon2 support in password_*. DIR is the Argon2 shared library path])
 
 if test "$PHP_PASSWORD_ARGON2" != "no"; then
   AC_MSG_CHECKING([for Argon2 library])