Perhaps you could help us understand what you see different about the
devel RPMs available for the different versions. While I agree that I do
not see any package filename with 'devel' in the name for MySQL 5.5, the
contents of the 5.0 one and the 5.5 package for libraries appears to be
identical in relevant ways. The following are checking the 5.5 and 5.0
packages available on the SDK x86_64 DVD1 ISO file that I just downloaded:

Code:
/mnt/test/suse/x86_64/libmysql55client_r18-32bit-5.5.43-0.7.3.x86_64.rpm
2018-06-26 07:05:34 Jobs:0 Err:0
ab@mybox:~> rpm -qlp
/mnt/test/suse/x86_64/libmysql55client_r18-32bit-5.5.43-0.7.3.x86_64.rpm
/usr/lib/libmysql55client_r.so.18
/usr/lib/libmysql55client_r.so.18.0.0
2018-06-26 07:05:54 Jobs:0 Err:0

ab@mybox:~> rpm -qlp
/mnt/test/suse/x86_64/libmysqlclient_r15-32bit-5.0.96-0.6.20.x86_64.rpm
/usr/lib/libmysqlclient_r.so.15
/usr/lib/libmysqlclient_r.so.15.0.0
/usr/lib/mysql
/usr/lib/mysql/libmysqlclient_r.so.15
/usr/lib/mysql/libmysqlclient_r.so.15.0.0
Going forward newer versions of the released product include the libraries
package (without 'devel' in its name) along with patches for the main
product, so everything should be downloaded, if applicable, at the same time.

The ISO I used came from
https://download.suse.com/protected/...d=GD_bL078XxY~

What's in a name? That which we call a rose by any other word would smell
as sweet;

--
Good luck.

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