Fix incorrect zlib linking in CI

When cross compiling, zlib couldn't be found because of a missing 'make
install'. As a result the compiled curl binaries do not support zlib.
Add 'make install' and also use the '--with-zlib' curl configure flag by
default to ensure a missing zlib will result in a failed build.

.github/workflows/build-and-test-make.yml

@@ -90,8 +90,9 @@ jobs:
           cd zlib-1.2.12
           CHOST=${{ matrix.host }} ./configure --prefix=${{ runner.temp }}/zlib
           make
+          make intsall
           # Make sure curl will link with libz.so.1 and not libz.so
-          rm -f libz.so
+          rm -f ${{ runner.temp }}/zlib/lib/libz.so
 
       - name: Run configure script
         if: matrix.arch == 'x86_64'

Makefile.in

@@ -372,6 +372,8 @@ $(CURL_VERSION)/.firefox: $(firefox_libs) $(CURL_VERSION).tar.xz $(CURL_VERSION)
 	  fi; \
 	  if test -n "$(with_zlib)"; then \
 	    config_flags+=" --with-zlib=$(with_zlib)"; \
+	  else \
+	    config_flags+=" --with-zlib"; \
 	  fi; \
 	  if test -n "$(with_libnssckbi)"; then \
 		config_flags+=" --with-libnssckbi=$(with_libnssckbi)"; \
@@ -410,6 +412,8 @@ $(CURL_VERSION)/.chrome: $(chrome_libs)	$(CURL_VERSION).tar.xz $(CURL_VERSION)/.
 	  fi; \
 	  if test -n "$(with_zlib)"; then \
 	    config_flags="$$config_flags --with-zlib=$(with_zlib)"; \
+	  else \
+	    config_flags+=" --with-zlib"; \
 	  fi; \
 	  if test -n "$(with_ca_bundle)"; then \
 		config_flags="$$config_flags --with-ca-bundle=$(with_ca_bundle)"; \