missing development files for groonga-normalizer-mysql at BuildRequires.

The package of `mysql-mroonga` depends `groonga-normalizer-mysql.pc` to compile.
But it has't contained `BuildRequires` in `mysql-mroonga-3.03.spec`.
It should be contain `groonga-normalizer-mysql-devel` instead of `groonga-normalizer-mysql` in `BuildRequires`.

## file list

```
$ rpm -ql groonga-normalizer-mysql
/usr/lib64/groonga
/usr/lib64/groonga/plugins
/usr/lib64/groonga/plugins/normalizers
/usr/lib64/groonga/plugins/normalizers/mysql.so
/usr/share/doc/groonga-normalizer-mysql
/usr/share/doc/groonga-normalizer-mysql-1.0.3
/usr/share/doc/groonga-normalizer-mysql-1.0.3/AUTHORS
/usr/share/doc/groonga-normalizer-mysql-1.0.3/COPYING
/usr/share/doc/groonga-normalizer-mysql-1.0.3/README
/usr/share/doc/groonga-normalizer-mysql/README.md
/usr/share/doc/groonga-normalizer-mysql/lgpl-2.0.txt

$ rpm -ql groonga-normalizer-mysql-devel
/usr/lib64/pkgconfig/groonga-normalizer-mysql.pc
```

## dependency list

```
$ rpm -qR groonga-normalizer-mysql
groonga-libs >= 3.0.3
libc.so.6()(64bit)
libc.so.6(GLIBC_2.2.5)(64bit)
libgroonga.so.0()(64bit)
rpmlib(CompressedFileNames) <= 3.0.4-1
rpmlib(PayloadFilesHavePrefix) <= 4.0-1
rtld(GNU_HASH)

$ rpm -qR groonga-normalizer-mysql-devel
/usr/bin/pkg-config
groonga-normalizer-mysql = 1.0.3-0.el6
rpmlib(CompressedFileNames) <= 3.0.4-1
rpmlib(PayloadFilesHavePrefix) <= 4.0-1
rpmlib(VersionedDependencies) <= 3.0.3-1
```