spec: use vendored zlib

cross-toolchain.spec

@@ -208,7 +208,6 @@ cd obj_binutils
 	--disable-nls \
 	--with-sysroot=%sysroot \
 	--with-build-sysroot=${stagedir}%sysroot \
-	--with-system-zlib \
 	--enable-plugins \
 %if "%target_arch" != "loongarch64"
 	--enable-gold=yes \
@@ -261,7 +260,6 @@ cd ../obj_gcc_bootstrap
 	--disable-libcilkrts \
 	--enable-version-specific-runtime-libs \
 	--with-gcc-major-version-only \
-	--with-system-zlib \
 %if "%target_arch" == "mipsel"
 	--with-arch-32=mips32r2 \
 	--with-fp-32=xx \
@@ -339,7 +337,6 @@ cd ../obj_gcc
 	--enable-version-specific-runtime-libs \
 	--disable-nls \
 	--disable-libsanitizer \
-	--with-system-zlib \
 %if "%target_arch" == "mipsel"
 	--with-arch-32=mips32r2 \
 	--with-fp-32=xx \