Add more support for Win64:

- Export .lib files for x64 instead of i386;
- Win64's malloc returns 16-byte aligned blocks.

Originally committed as revision 13147 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1199,6 +1199,11 @@ case $target_os in
         ;;
     mingw32*)
         target_os=mingw32
+        LIBTARGET=i386
+        if test $arch = x86_64; then
+            disable need_memalign
+            LIBTARGET=x64
+        fi
         shlibdir="$bindir"
         VHOOKSHFLAGS='-shared -L$(BUILD_ROOT)/libavformat -L$(BUILD_ROOT)/libavcodec -L$(BUILD_ROOT)/libavutil'
         VHOOKLIBS='-lavformat$(BUILDSUF) -lavcodec$(BUILDSUF) -lavutil$(BUILDSUF) $(EXTRALIBS)'
@@ -1212,7 +1217,7 @@ case $target_os in
         EXESUF=".exe"
         SLIBNAME_WITH_VERSION='$(SLIBPREF)$(FULLNAME)-$(LIBVERSION)$(SLIBSUF)'
         SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)'
-        SLIB_EXTRA_CMD='-lib /machine:i386 /def:$$(@:$(SLIBSUF)=.def) /out:$(SUBDIR)$(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.lib)'
+        SLIB_EXTRA_CMD='-lib /machine:$(LIBTARGET) /def:$$(@:$(SLIBSUF)=.def) /out:$(SUBDIR)$(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.lib)'
         SLIB_INSTALL_EXTRA_CMD='-install -m 644 $(SUBDIR)$(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.lib) "$(SHLIBDIR)/$(SLIBNAME:$(SLIBSUF)=.lib)"; \
             install -m 644 $(SUBDIR)$(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.lib) "$(SHLIBDIR)/$(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.lib)"'
         SLIB_UNINSTALL_EXTRA_CMD='rm -f "$(SHLIBDIR)/$(SLIBNAME:$(SLIBSUF)=.lib)"'
@@ -2051,6 +2056,7 @@ get_version LIBAVFILTER libavfilter/avfilter.h
 if enabled shared; then
     echo "BUILD_SHARED=yes" >> config.mak
     echo "PIC=-fPIC -DPIC" >> config.mak
+    echo "LIBTARGET=${LIBTARGET}" >> config.mak
     echo "SLIBNAME=${SLIBNAME}" >> config.mak
     echo "SLIBNAME_WITH_VERSION=${SLIBNAME_WITH_VERSION}" >> config.mak
     echo "SLIBNAME_WITH_MAJOR=${SLIBNAME_WITH_MAJOR}" >> config.mak