Fix jpeg-turbo on windows 64 bit

This fix supports building jpeg-turbo on both cygwin 32 nd 64 bit.
When only cygwin 64 bit is used, then it can be simplified by
passing BUILD_PLATFORM to configure script on all platforms.

Change-Id: Id335282f1761fcf7313fb18a6b9250e5eac392e4
Reviewed-on: https://gerrit.libreoffice.org/14315Tested-by: Michael Stahl <mstahl@redhat.com>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

external/jpeg-turbo/ExternalProject_jpeg-turbo.mk

@@ -25,7 +25,7 @@ $(call gb_ExternalProject_get_state_target,jpeg-turbo,build) : $(call gb_Externa
 $(call gb_ExternalProject_get_state_target,jpeg-turbo,configure) :
 	$(call gb_ExternalProject_run,configure,\
 		MAKE=$(MAKE) ./configure \
-			--build=$(if $(filter WNT,$(OS)),i686-pc-cygwin,$(BUILD_PLATFORM)) \
+			--build=$(if $(filter WNT,$(OS)),$(if $(filter INTEL,$(CPU)),i686-pc-cygwin,x86_64-pc-cygwin),$(BUILD_PLATFORM)) \
 			--with-pic \
 			--enable-static \
 			--disable-shared \