configure: Fixes to make SDL link as C++ on Haiku.

Fixes #4590.

Makefile.in

@@ -30,6 +30,7 @@ AR	= @AR@
 RANLIB	= @RANLIB@
 RC	= @RC@
 LINKER = @LINKER@
+LIBTOOLLINKERTAG = @LIBTOOLLINKERTAG@
 
 TARGET  = libSDL2.la
 OBJECTS = @OBJECTS@
@@ -153,13 +154,13 @@ update-revision:
 .PHONY: all update-revision install install-bin install-hdrs install-lib install-data uninstall uninstall-bin uninstall-hdrs uninstall-lib uninstall-data clean distclean dist $(OBJECTS:.lo=.d)
 
 $(objects)/$(TARGET): $(GEN_HEADERS) $(GEN_OBJECTS) $(OBJECTS) $(VERSION_OBJECTS)
-	$(RUN_CMD_LTLINK)$(LIBTOOL) --tag=CC --mode=link $(LINKER) -o $@ $(OBJECTS) $(GEN_OBJECTS) $(VERSION_OBJECTS) $(LDFLAGS) $(EXTRA_LDFLAGS) $(LT_LDFLAGS)
+	$(RUN_CMD_LTLINK)$(LIBTOOL) --tag=$(LIBTOOLLINKERTAG) --mode=link $(LINKER) -o $@ $(OBJECTS) $(GEN_OBJECTS) $(VERSION_OBJECTS) $(LDFLAGS) $(EXTRA_LDFLAGS) $(LT_LDFLAGS)
 
 $(objects)/$(SDLMAIN_TARGET): $(SDLMAIN_OBJECTS)
-	$(RUN_CMD_LTLINK)$(LIBTOOL) --tag=CC --mode=link $(LINKER) -static -o $@ $(SDLMAIN_OBJECTS) -rpath $(libdir)
+	$(RUN_CMD_LTLINK)$(LIBTOOL) --tag=$(LIBTOOLLINKERTAG) --mode=link $(LINKER) -static -o $@ $(SDLMAIN_OBJECTS) -rpath $(libdir)
 
 $(objects)/$(SDLTEST_TARGET): $(SDLTEST_OBJECTS)
-	$(RUN_CMD_LTLINK)$(LIBTOOL) --tag=CC --mode=link $(LINKER) -static -o $@ $(SDLTEST_OBJECTS) -rpath $(libdir)
+	$(RUN_CMD_LTLINK)$(LIBTOOL) --tag=$(LIBTOOLLINKERTAG) --mode=link $(LINKER) -static -o $@ $(SDLTEST_OBJECTS) -rpath $(libdir)
 
 install: all install-bin install-hdrs install-lib install-data
 install-bin:

configure

@@ -690,6 +690,7 @@ ALSA_CFLAGS
 POW_LIB
 LIBOBJS
 ALLOCA
+LIBTOOLLINKERTAG
 LINKER
 PKG_CONFIG_LIBDIR
 PKG_CONFIG_PATH
@@ -16020,13 +16021,16 @@ esac
 case "$host" in
     *-*-haiku*)
         LINKER='$(CXX)'
+        LIBTOOLLINKERTAG='CXX'
         ;;
     *)
         LINKER='$(CC)'
+        LIBTOOLLINKERTAG='CC'
         ;;
 esac
 
 
+
 if test x$srcdir != x.; then
     INCLUDE="-Iinclude $INCLUDE"
 elif test -d .git; then

configure.ac

@@ -85,12 +85,15 @@ dnl use CXX for linker on Haiku
 case "$host" in
     *-*-haiku*)
         LINKER='$(CXX)'
+        LIBTOOLLINKERTAG='CXX'
         ;;
     *)
         LINKER='$(CC)'
+        LIBTOOLLINKERTAG='CC'
         ;;
 esac
 AC_SUBST(LINKER)
+AC_SUBST(LIBTOOLLINKERTAG)
 
 if test x$srcdir != x.; then
     INCLUDE="-Iinclude $INCLUDE"