RFR: JDK-8196951: jdk build fails with clang: error: no such file or directory: '@LIBZ_CFLAGS@'

[Erik Joelsson]

It seems my recent changes has caused yet another build failure. I'm 
puzzled over why this worked in our internal CI builds but fails in 
other situations. Some toolchains must simply be accepting @LIBZ_CFLAGS@ 
on the command line. Anyway, the fix is to make sure the variables are 
always defined in configure:

Bug: https://bugs.openjdk.java.net/browse/JDK-8196951

Patch:

diff -r 8cc67294ec56 make/autoconf/lib-bundled.m4
--- a/make/autoconf/lib-bundled.m4
+++ b/make/autoconf/lib-bundled.m4
@@ -209,6 +209,8 @@
      AC_MSG_ERROR([Invalid value for --with-zlib: ${with_zlib}, use 
'system' or 'bundled'])
    fi

+  LIBZ_CFLAGS=""
+  LIBZ_LIBS=""
    if test "x$USE_EXTERNAL_LIBZ" = "xfalse"; then
      LIBZ_CFLAGS="$LIBZ_CFLAGS 
-I$TOPDIR/src/java.base/share/native/libzip/zlib"
    else


/Erik