Enable ORCA on macOS on Travis

We disabled ORCA in the macOS Travis build in commit 649ee57d
(#10068) when we thought builds timed out because the build machines
were underpowered. Turns out we made a mistake in 649ee57d where
the mac build was just broken (see fix in commit b371e592 #10147).
Now that all the pieces are in place, I can think of no reason to
neglect this compile-time coverage in Travis.

Given that the macOS VMs in Travis are generally underpowered, build
with -O0 to expedite the process.

.travis.yml

@@ -190,7 +190,7 @@ script:
             --prefix=${TRAVIS_BUILD_DIR}/gpsql \
             --with-perl \
             --with-python \
-            --disable-orca \
+            --enable-orca \
             --enable-orafce \
             --disable-gpfdist \
             --disable-pxf \
@@ -198,8 +198,9 @@ script:
             --without-zstd \
             --with-includes=$(brew --prefix xerces-c)/include \
             --with-libs=$(brew --prefix xerces-c)/lib \
+            CFLAGS='-O0' CXXFLAGS='-O0' \
             $C
-        make -s install
+        travis_wait 40 make -s install
         source ${TRAVIS_BUILD_DIR}/gpsql/greenplum_path.sh
         make -s unittest-check
       fi