Revert "configure: Stop using dlltool to create an import library"

This reverts commit 67c72f08.

While the linker produced import libraries might work with MSVC in
simple test cases, they don't if e.g. linking to multiple GNU ld
produced import libraries at the same time. (They end up importing
functions from the wrong libraries.) The ones produced by dlltool
work fine though.

This issue was pointed out by Hendrik Leppkes.
Signed-off-by: Martin Storsjö <martin@martin.st>

configure

@@ -3891,6 +3891,10 @@ case $target_os in
         ;;
     mingw32*|mingw64*)
         target_os=mingw32
+        LIBTARGET=i386
+        if enabled x86_64; then
+            LIBTARGET="i386:x86-64"
+        fi
         if enabled shared; then
             # Cannot build both shared and static libs when using dllimport.
             disable static
@@ -3902,7 +3906,7 @@ case $target_os in
         SLIBSUF=".dll"
         SLIBNAME_WITH_VERSION='$(SLIBPREF)$(NAME)-$(LIBVERSION)$(SLIBSUF)'
         SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(NAME)-$(LIBMAJOR)$(SLIBSUF)'
-        SLIB_EXTRA_CMD='cp $(SUBDIR)lib$(SLIBNAME:$(SLIBSUF)=.dll.a) $(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
+        SLIB_EXTRA_CMD=-'$(DLLTOOL) -m $(LIBTARGET) -d $$(@:$(SLIBSUF)=.def) -l $(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib) -D $(SLIBNAME_WITH_MAJOR)'
         SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)'
         SLIB_INSTALL_LINKS=
         SLIB_INSTALL_EXTRA_SHLIB='$(SLIBNAME:$(SLIBSUF)=.lib)'
@@ -3910,6 +3914,7 @@ case $target_os in
         SLIB_CREATE_DEF_CMD='EXTERN_PREFIX="$(EXTERN_PREFIX)" AR="$(AR_CMD)" NM="$(NM_CMD)" $(SRC_PATH)/compat/windows/makedef $(SUBDIR)lib$(NAME).ver $(OBJS) > $$(@:$(SLIBSUF)=.def)'
         SHFLAGS='-shared -Wl,--out-implib,$(SUBDIR)lib$(SLIBNAME:$(SLIBSUF)=.dll.a) -Wl,--enable-auto-image-base $$(@:$(SLIBSUF)=.def)'
         enabled x86_64 && objformat="win64" || objformat="win32"
+        dlltool="${cross_prefix}dlltool"
         ranlib=:
         enable dos_paths
         ;;
@@ -5248,6 +5253,7 @@ X86ASM_O=$X86ASM_O
 LD_O=$LD_O
 LD_LIB=$LD_LIB
 LD_PATH=$LD_PATH
+DLLTOOL=$dlltool
 LDFLAGS=$LDFLAGS
 LDEXEFLAGS=$LDEXEFLAGS
 LDSOFLAGS=$LDSOFLAGS
@@ -5294,6 +5300,7 @@ LIB_INSTALL_EXTRA_CMD=$LIB_INSTALL_EXTRA_CMD
 EXTRALIBS=$extralibs
 COMPAT_OBJS=$compat_objs
 INSTALL=install
+LIBTARGET=${LIBTARGET}
 SLIBNAME=${SLIBNAME}
 SLIBNAME_WITH_VERSION=${SLIBNAME_WITH_VERSION}
 SLIBNAME_WITH_MAJOR=${SLIBNAME_WITH_MAJOR}