GHA/linux: build `-O3` job with unity batches to save 10-15s

Before (build, test run):
https://github.com/curl/curl/actions/runs/16974205126/job/48118716664 25s, 12m56
https://github.com/curl/curl/actions/runs/16973102133/job/48114977897 24s, 12m51

After, with batch size 50 (build, test run):
https://github.com/curl/curl/actions/runs/17250901063/job/48952645881?pr=18293 16s, 12m51
https://github.com/curl/curl/actions/runs/17250901063/job/48953665204?pr=18293 17s, 12m42

Closes #18293

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 8b1c37ba069f0f75817684c9b752d6c3372e9ce9..656851030b1325f131349afc0e03c10df574a67b 100644 (file)
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -173,7 +173,7 @@ jobs:
           - name: 'openssl -O3 libssh valgrind'
             install_packages: zlib1g-dev libssh-dev valgrind
             CFLAGS: -O3
-            generate: -DENABLE_DEBUG=ON -DCURL_USE_LIBSSH=ON
+            generate: -DENABLE_DEBUG=ON -DCURL_USE_LIBSSH=ON -DCMAKE_UNITY_BUILD_BATCH_SIZE=50
 
           - name: 'openssl clang krb5 openldap static'
             install_steps: openldap-static