configure.ac: generate debug symbols for Win

<https://stackoverflow.com/questions/74416539/clang-14-does-not-generate-pdb-file>

Set it only when linking, not for configure.

.github/scripts/Windows/prepare_msys.sh

@@ -46,7 +46,7 @@ PACMAN_INSTALL='pacman -Sy --needed --noconfirm --disable-download-timeout'
 MINGW_PACKAGE_PREFIX=mingw-w64-clang-x86_64
 m=$MINGW_PACKAGE_PREFIX
 $PACMAN_INSTALL automake autoconf git make pkgconf \
-        $m-clang $m-winpthreads \
+        $m-clang $m-lld $m-winpthreads \
         $m-gcc-compat \
         unzip zip
 $PACMAN_INSTALL $m-asciidoc \

Makefile.in

@@ -241,7 +241,8 @@ src/dir-stamp:
 
 $(TARGET): src/dir-stamp $(ULTRAGRID_OBJS) $(GENERATED_HEADERS) $(BIN_DEPS)
 	$(MKDIR_P) $$(dirname $@)
-	$(LINKER) $(LDFLAGS) $(ULTRAGRID_OBJS) $(LIBS) $(ULTRAGRID_LIBS) -o $(TARGET)
+	$(LINKER) $(LDFLAGS) @UV_LDFLAGS@ $(ULTRAGRID_OBJS) $(LIBS) $(ULTRAGRID_LIBS)\
+	  -o $(TARGET)
 	@if [ -n '@DLL_LIBS@' ]; then $(INSTALL) -m 644 @DLL_LIBS@ bin; fi
 
 $(REFLECTOR_TARGET): src/dir-stamp $(REFLECTOR_OBJS) $(GENERATED_HEADERS) bin/hd-rum-av
@@ -554,6 +555,7 @@ clean:
 	$(COND_SILENCE)-rm -rf @TOREMOVE@ @MODULES@ @LIB_GENERATED_HEADERS@
 	$(COND_SILENCE)-rm -rf $(DEP_FILES)
 	$(COND_SILENCE)-rm -rf bin/shaders
+	$(COND_SILENCE)-rm -f bin/uv.pdb
 	$(COND_SILENCE)if [ -f "gui/QT/Makefile" ]; then make -C gui/QT/ distclean; fi
 
 distclean: clean
@@ -690,6 +692,10 @@ install: all
 	if [ -n "@VULKAN@" ]; then\
 		$(INSTALL) -D -m 644 "$(srcdir)/share/ultragrid/vulkan_shaders/"* -t "$(DESTDIR)$(datadir)/ultragrid/vulkan_shaders"; \
 	fi
+	if [ -f bin/uv.pdb ]; then\
+		$(INSTALL) -m 644 bin/uv.pdb $(DESTDIR)$(bindir); \
+	fi
+
 uninstall:
 	$(RM) $(DESTDIR)$(bindir)/uv
 	$(RM) $(DESTDIR)$(bindir)/hd-rum-transcode
@@ -710,5 +716,6 @@ uninstall:
 		rmdir $(DESTDIR)$(datadir)/ultragrid/vulkan_shaders;\
 		rmdir $(DESTDIR)$(datadir)/ultragrid;\
 	fi
+	$(RM) $(DESTDIR)$(bindir)/uv.pdb
 
 # vim: set noexpandtab

configure.ac

@@ -174,12 +174,23 @@ if test $system = Windows; then
 	LIBS="$LIBS -lsetupapi -lws2_32 -liphlpapi -lole32 -loleaut32"
 	LIBS="$LIBS -ldbghelp"
 	AC_CHECK_FUNCS(SetThreadDescription)
+        if $CXX -dM -E - </dev/null | grep clang >/dev/null; then
+                AC_CHECK_PROG([LLD], [lld], [yes])
+                if test "$LLD" = yes; then
+                        COMMON_FLAGS="${COMMON_FLAGS:+$COMMON_FLAGS }-gcodeview"
+                        UV_LDFLAGS="-fuse-ld=lld -g -Wl,--pdb=bin/uv.pdb"
+                fi
+        fi
+        if ! expr "x$COMMON_FLAGS" : '.*gcodeview' >/dev/null; then
+                UG_MSG_WARN([Windows stacktrace will not be available.])
+        fi
 fi
 
 LINKER=$CXX
 
 AC_SUBST(LINKER)
 AC_SUBST(LDFLAGS)
+AC_SUBST(UV_LDFLAGS)
 AC_SUBST(CXXFLAGS)
 
 AC_ARG_ENABLE(depends-version-check,