### Description

I got parse error in config file. I am using MSRP module and if I try to use (to print a log) with `$msrp(msgid)` I get an error. According to the psudovariables documentation should work.

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### Troubleshooting

#### Reproduction

Just use within an event_route[msrp:frame-in] block $msrp(msgid).

#### Log Messages

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``` 0(9827) ERROR: msrp [msrp_vars.c:118]: pv_parse_msrp_name(): unknown PV msrp name msgid 0(9827) ERROR: <core> [pvapi.c:877]: pv_parse_spec2(): pvar "msrp" has an invalid name param [msgid] 0(9827) ERROR: <core> [pvapi.c:1032]: pv_parse_spec2(): wrong char [)/41] in [$msrp(msgid)] at [11 (5)] 0(9827) : <core> [cfg.y:3368]: yyerror_at(): parse error in config file route.cfg, line 649, column 40-51: Can't get from cache: $msrp(msgid) ERROR: bad config file (1 errors) ```

### Additional Information

* **Kamailio Version** -4.4.5

* **Operating System**:

<!-- Details about the operating system, the type: Linux (e.g.,: Debian 8.4, Ubuntu 16.04, CentOS 7.1, ...), MacOS, xBSD, Solaris, ...; Kernel details (output of `uname -a`) -->

``` Linux test 2.6.32-642.15.1.el6.x86_64 #1 SMP Fri Feb 24 14:31:22 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux ```