Fix a missing return in the C client sslConfig_create function.

[brendandburns]

Fixes a missing return in the sslConfig_create function in the C client templates.

cc @zhemant @ityuhui @michelealbano

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[wing328]

LGTM

[ityuhui]

It's a very important patch. Thank you @brendandburns and @wing328

[wing328]

I used Clang Static Analyzer to detect potential issues with the C Petstore client and it's able to detect issues fixed by this PR.

For the full report, please refer to #7221 and we'll review and address those issues with separate PRs.