Although CMake keeps time stamps to remember how far it got in an ExternalProject_Add()

build, it throws the time stamps away when there are edits to the CMakeLists.txt portion
pertaining to the external project.  Only a 'make clean' would remove the untarred tree.
This patch removes the need to do a make clean when changing the ExternalProject_Add()
text pertinent to patching.

Fixes bug 1250222 in KiCad-Winbuilder

CMakeModules/download_boost.cmake

@@ -121,8 +121,12 @@ ExternalProject_Add( boost
     URL_MD5         ${BOOST_MD5}
 
     # The patch command executes with the working directory set to <SOURCE_DIR>
-    PATCH_COMMAND   bzr patch -p0 "${PROJECT_SOURCE_DIR}/patches/boost_minkowski.patch"
+    # Revert the branch to pristine before applying patch sets as bzr patch
+    # fails when applying a patch to the branch twice and doesn't have a switch
+    # to ignore previously applied patches
+    PATCH_COMMAND   bzr revert
         # PATCH_COMMAND continuation (any *_COMMAND here can be continued with COMMAND):
+        COMMAND     bzr patch -p0 "${PROJECT_SOURCE_DIR}/patches/boost_minkowski.patch"
         COMMAND     bzr patch -p0 "${PROJECT_SOURCE_DIR}/patches/boost_cstdint.patch"
 
     # [Mis-]use this step to erase all the boost headers and libraries before

CMakeModules/download_openssl.cmake

@@ -58,7 +58,13 @@ ExternalProject_Add(
     # PATCH_COMMAND patch -p0 < ${PROJECT_SOURCE_DIR}/patches/openssl-1.0.1e.patch
 
     # This one requires the bzr commit below, since bzr patch only knows a working tree.
-    PATCH_COMMAND bzr patch -p0 ${PROJECT_SOURCE_DIR}/patches/openssl-1.0.1e.patch
+    
+    # Revert the branch to pristine before applying patch sets as bzr patch
+    # fails when applying a patch to the branch twice and doesn't have a switch
+    # to ignore previously applied patches
+    PATCH_COMMAND   bzr revert
+        # PATCH_COMMAND continuation (any *_COMMAND here can be continued with COMMAND):
+        COMMAND     bzr patch -p0 ${PROJECT_SOURCE_DIR}/patches/openssl-1.0.1e.patch
 
     CONFIGURE_COMMAND
             ${CMAKE_COMMAND}