https://git.alpinelinux.org/aports/tree/community/qt5-qtwebengine/qt-musl-resolve.patch

A better method would be to check for these functions in the build system
but as QMake is getting replaced by CMake in Qt6 I did not bother.

---
 .../net/dns/dns_config_service_posix.cc       |  4 +++
 src/3rdparty/chromium/net/dns/dns_reloader.cc |  4 +++
 src/3rdparty/chromium/net/dns/resolv_compat.h | 29 +++++++++++++++++++
 3 files changed, 37 insertions(+)
 create mode 100644 src/3rdparty/chromium/net/dns/resolv_compat.h

diff --git a/src/3rdparty/chromium/net/dns/dns_config_service_posix.cc b/src/3rdparty/chromium/net/dns/dns_config_service_posix.cc
index 5a4aead0a..0e4480d16 100644
--- a/src/3rdparty/chromium/net/dns/dns_config_service_posix.cc
+++ b/src/3rdparty/chromium/net/dns/dns_config_service_posix.cc
@@ -8,6 +8,10 @@
 #include <string>
 #include <type_traits>
 
+#if !defined(__GLIBC__)
+#include "resolv_compat.h"
+#endif
+
 #include "base/bind.h"
 #include "base/files/file.h"
 #include "base/files/file_path.h"
diff --git a/src/3rdparty/chromium/net/dns/dns_reloader.cc b/src/3rdparty/chromium/net/dns/dns_reloader.cc
index 0672e711a..298489866 100644
--- a/src/3rdparty/chromium/net/dns/dns_reloader.cc
+++ b/src/3rdparty/chromium/net/dns/dns_reloader.cc
@@ -9,6 +9,10 @@
 
 #include <resolv.h>
 
+#if !defined(__GLIBC__)
+#include "resolv_compat.h"
+#endif
+
 #include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "base/notreached.h"
diff --git a/src/3rdparty/chromium/net/dns/resolv_compat.h b/src/3rdparty/chromium/net/dns/resolv_compat.h
new file mode 100644
index 000000000..4f0e852a1
--- /dev/null
+++ b/src/3rdparty/chromium/net/dns/resolv_compat.h
@@ -0,0 +1,29 @@
+#if !defined(__GLIBC__)
+/***************************************************************************
+ * resolv_compat.h
+ *
+ * Mimick GLIBC's res_ninit() and res_nclose() for musl libc
+ * Note: res_init() is actually deprecated according to
+ * http://docs.oracle.com/cd/E36784_01/html/E36875/res-nclose-3resolv.html
+ **************************************************************************/
+#include <string.h>
+
+static inline int res_ninit(res_state statp)
+{
+	int rc = res_init();
+	if (statp != &_res) {
+		memcpy(statp, &_res, sizeof(*statp));
+	}
+	return rc;
+}
+
+static inline int res_nclose(res_state statp)
+{
+	if (!statp)
+		return -1;
+	if (statp != &_res) {
+		memset(statp, 0, sizeof(*statp));
+	}
+	return 0;
+}
+#endif
-- 
2.35.1