gnu: podofo: Add patch to fix build.

* gnu/packages/patches/podofo-cmake-3.12.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/pdf.scm (podofo)[source]: Add patch.

gnu/local.mk

@@ -1055,6 +1055,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/plink-1.07-unclobber-i.patch		\
   %D%/packages/patches/plink-endian-detection.patch		\
   %D%/packages/patches/plotutils-libpng-jmpbuf.patch		\
+  %D%/packages/patches/podofo-cmake-3.12.patch			\
   %D%/packages/patches/poppler-CVE-2018-19149.patch		\
   %D%/packages/patches/portaudio-audacity-compat.patch		\
   %D%/packages/patches/portmidi-modular-build.patch		\

gnu/packages/patches/podofo-cmake-3.12.patch

@@ -0,0 +1,19 @@
+The build fails with cmake 3.12.0.  This patch will be obsolete with the next
+release.
+
+https://sourceforge.net/p/podofo/tickets/24/attachment/podofo-cmake-3.12.patch
+
+
+--- a/test/TokenizerTest/CMakeLists.txt	2018-07-20 18:26:02.921494293 +0200
++++ b/test/TokenizerTest/CMakeLists.txt	2018-07-20 18:34:53.727136443 +0200
+@@ -2,10 +2,3 @@
+ TARGET_LINK_LIBRARIES(TokenizerTest ${PODOFO_LIB} ${PODOFO_LIB_DEPENDS})
+ SET_TARGET_PROPERTIES(TokenizerTest PROPERTIES COMPILE_FLAGS "${PODOFO_CFLAGS}")
+ ADD_DEPENDENCIES(TokenizerTest ${PODOFO_DEPEND_TARGET})
+-
+-# Copy the test samples over to the build tree
+-ADD_CUSTOM_COMMAND(
+-    TARGET TokenizerTest
+-    POST_BUILD
+-    COMMAND "${CMAKE_COMMAND}" -E copy_directory "${CMAKE_CURRENT_SOURCE_DIR}/objects" "${CMAKE_CURRENT_BINARY_DIR}/objects"
+-    )

gnu/packages/pdf.scm

@@ -557,7 +557,8 @@ interaction.")
                                   "/podofo-" version ".tar.gz"))
               (sha256
                (base32
-                "0wj0y4zcmj4q79wrn3vv3xq4bb0vhhxs8yifafwy9f2sjm83c5p9"))))
+                "0wj0y4zcmj4q79wrn3vv3xq4bb0vhhxs8yifafwy9f2sjm83c5p9"))
+              (patches (search-patches "podofo-cmake-3.12.patch"))))
     (build-system cmake-build-system)
     (native-inputs
      `(("cppunit" ,cppunit)