ci: enforce ccache for macos meson run

Summary:
While we set CC="ccache gcc" as an env var in Travis it gets overridden
at some point before meson is run. This results in a situation where we
have ccache enabled for g++, but not for gcc. Enforcing the setting
directly before meson again to make sure it gets picked up correctly.

I have seen build time improvements on Travis with up to 7 minutes
with this in an optimal case (rebuild existing job). It should shave off
at least a few minutes from every build even with bigger changes.
Depends on D9160

Reviewers: zmike, bu5hm4n

Reviewed By: zmike

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D9161

.ci/ci-configure.sh

@@ -83,6 +83,7 @@ else
   export LDFLAGS="-L/usr/local/opt/openssl/lib $LDFLAGS"
   LIBFFI_VER=$(brew list --versions libffi|head -n1|cut -d' ' -f2)
   export PKG_CONFIG_PATH="/usr/local/opt/openssl/lib/pkgconfig:/usr/local/Cellar/libffi/$LIBFFI_VER/lib/pkgconfig"
+  export CC="ccache gcc"
   travis_fold meson meson
   mkdir build && meson build -Decore-imf-loaders-disabler=scim,ibus -Dx11=false -Davahi=false -Dbindings=luajit -Deeze=false -Dsystemd=false -Dnls=false -Dcocoa=true -Demotion-loaders-disabler=gstreamer,gstreamer1,libvlc,xine
   travis_endfold meson