meson: move zlib detection to meson

Meson includes the same logic that tries to look for -lz if
pkg-config (and cmake) cannot find zlib.  The undocumented
--disable-zlib-test option becomes a no-op.

There is still an instance of "-lz" in the LIBS directory.
It will go away as soon as tests are converted to meson,
because the zlib dependency does not propagate from libblock.fa
to the Makefile-build unit tests.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

configure

@@ -502,7 +502,6 @@ opengl=""
 opengl_dmabuf="no"
 cpuid_h="no"
 avx2_opt=""
-zlib="yes"
 capstone=""
 lzo=""
 snappy=""
@@ -1428,7 +1427,7 @@ for opt do
   ;;
   --enable-usb-redir) usb_redir="yes"
   ;;
-  --disable-zlib-test) zlib="no"
+  --disable-zlib-test)
   ;;
   --disable-lzo) lzo="no"
   ;;
@@ -3904,30 +3903,6 @@ if ! compile_prog "$glib_cflags -Werror" "$glib_libs" ; then
     fi
 fi
 
-#########################################
-# zlib check
-
-if test "$zlib" != "no" ; then
-    if $pkg_config --exists zlib; then
-        zlib_cflags=$($pkg_config --cflags zlib)
-        zlib_libs=$($pkg_config --libs zlib)
-        QEMU_CFLAGS="$zlib_cflags $QEMU_CFLAGS"
-        LIBS="$zlib_libs $LIBS"
-    else
-        cat > $TMPC << EOF
-#include <zlib.h>
-int main(void) { zlibVersion(); return 0; }
-EOF
-        if compile_prog "" "-lz" ; then
-            zlib_libs=-lz
-            LIBS="$LIBS $zlib_libs"
-        else
-            error_exit "zlib check failed" \
-                "Make sure to have the zlib libs and headers installed."
-        fi
-    fi
-fi
-
 ##########################################
 # SHA command probe for modules
 if test "$modules" = yes; then
@@ -7135,11 +7110,6 @@ fi
 if test "$posix_memalign" = "yes" ; then
   echo "CONFIG_POSIX_MEMALIGN=y" >> $config_host_mak
 fi
-if test "$zlib" != "no" ; then
-    echo "CONFIG_ZLIB=y" >> $config_host_mak
-    echo "ZLIB_CFLAGS=$zlib_cflags" >> $config_host_mak
-    echo "ZLIB_LIBS=$zlib_libs" >> $config_host_mak
-fi
 if test "$spice" = "yes" ; then
   echo "CONFIG_SPICE=y" >> $config_host_mak
   echo "SPICE_CFLAGS=$spice_cflags" >> $config_host_mak

meson.build

@@ -134,11 +134,7 @@ if 'CONFIG_AUTH_PAM' in config_host
   pam = cc.find_library('pam')
 endif
 libaio = cc.find_library('aio', required: false)
-zlib = not_found
+zlib = dependency('zlib', required: true, static: enable_static)
-if 'CONFIG_ZLIB' in config_host
-  zlib = declare_dependency(compile_args: config_host['ZLIB_CFLAGS'].split(),
-                            link_args: config_host['ZLIB_LIBS'].split())
-endif
 linux_io_uring = not_found
 if 'CONFIG_LINUX_IO_URING' in config_host
   linux_io_uring = declare_dependency(compile_args: config_host['LINUX_IO_URING_CFLAGS'].split(),