qtbase: use v5.12.0 as base

* restore 0018-Fix-compile-issue-with-gcc-9.patch which is only in v5.12.1
* zlib detection got broken probably in:
  commit e80bf655e922e9864f8843b5e7bbb47019a6d95a
  Author: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
  Date:   Thu Dec 7 19:30:07 2017 +0100

    configure: verify header presence against sources

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/recipes-qt/qt5/qtbase/0018-Fix-compile-issue-with-gcc-9.patch b/recipes-qt/qt5/qtbase/0018-Fix-compile-issue-with-gcc-9.patch
new file mode 100644
index 00000000..db79e846
--- /dev/null
+++ b/recipes-qt/qt5/qtbase/0018-Fix-compile-issue-with-gcc-9.patch
@@ -0,0 +1,28 @@
+From cde196cf74805cc0f47fbebce884a871859862b2 Mon Sep 17 00:00:00 2001
+From: Allan Sandfeld Jensen <allan.jensen@qt.io>
+Date: Tue, 13 Nov 2018 16:00:23 +0100
+Subject: [PATCH] Fix compile issue with gcc 9
+
+It appears messenne_twisters in the latest libstdc++ has one more
+requirement before it is willing to construct with our
+SystemGenerator struct as an sseq provider.
+
+Change-Id: If38151d1fa6f40a80274acc26d9ed6b4ac6049fe
+Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
+Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
+---
+ src/corelib/global/qrandom.cpp | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/src/corelib/global/qrandom.cpp b/src/corelib/global/qrandom.cpp
+index 23e5e499b2..03534cf453 100644
+--- a/src/corelib/global/qrandom.cpp
++++ b/src/corelib/global/qrandom.cpp
+@@ -218,6 +218,7 @@ struct QRandomGenerator::SystemGenerator
+ #endif // Q_OS_WINRT
+ 
+     static SystemGenerator &self();
++    typedef quint32 result_type;
+     void generate(quint32 *begin, quint32 *end) Q_DECL_NOEXCEPT_EXPR(FillBufferNoexcept);
+ 
+     // For std::mersenne_twister_engine implementations that use something