when cross-compiling: -system-zlib checks the target but is also used for the built tools. This breaks when the build host has no zlib headers

When cross-compiling:
./configure -system-zlib ...
This checks if zlib is available on the target but it does not check the build system.
However in src/tools/bootstrap/bootstrap.pro the result of this test is used.
With zlib on the target but not the build system compiling fails with missing zlib headers.
For cross-compiling the bootstrap stuff should probably always be built with the internal zlib:

src/tools/bootstrap/bootstrap.pro | 2 +-
1 file changed, 1 insertion, 1 deletion

Index: b/src/tools/bootstrap/bootstrap.pro
===================================================================
— a/src/tools/bootstrap/bootstrap.pro
+++ b/src/tools/bootstrap/bootstrap.pro
@@ -95,7 +95,7 @@ macx:

-contains(QT_CONFIG, zlib) {
+contains(QT_CONFIG, zlib)|cross_compile {
INCLUDEPATH += ../../3rdparty/zlib
SOURCES+= \
../3rdparty/zlib/adler32.c \