Describe the bug
Here https://github.com/gogs/gogs/blob/master/cmd/web.go#L724 we set TLS server cipher suits in our code, but it only contains suits about RSA.

ECDSA cipher suits like TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 are not added.

Meanwhile, the server preferred cure is all ECC cure https://github.com/gogs/gogs/blob/master/cmd/web.go#L721

I'm happy to open a pull request to fix this problem

To Reproduce
Start gogs with ECC certificate

Expected behavior
It should work with ECC certificate

Screenshots

CONNECTED(00000003)
3069354000:error:14094410:SSL routines:ssl3_read_bytes:sslv3 alert handshake failure:../ssl/record/rec_layer_s3.c:1536:SSL alert number 40
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 7 bytes and written 283 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)
---

Additional context

• Gogs version (or commit ref): 0.11.91
• Git version:
• Operating system:
• Database (replace [ ] with [x]):
  • PostgreSQL
  • MySQL
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gogs.io:
  • Yes: provide example URL
  • No: It needs start server with another certificate
• Log gist (usually found in log/gogs.log):
  2019/08/24 23:50:47 http: TLS handshake error from x.x.x.x:60825: tls: no cipher suite supported by both client and server