The master "CMakeLists.txt" listed "pandoc" as an optional dependency,
but subsequent "make install" fails if "pandoc" is missing.
This patch makes "pandoc" really optional.
diff -ru rdma-core-25.0.orig/CMakeLists.txt rdma-core-25.0/CMakeLists.txt
--- rdma-core-25.0.orig/CMakeLists.txt	2019-07-26 02:17:21.000000000 +0800
+++ rdma-core-25.0/CMakeLists.txt	2019-07-31 00:08:41.485085990 +0800
@@ -602,11 +602,17 @@
 add_subdirectory(kernel-headers)
 # Libraries
 add_subdirectory(libibumad)
+if (PANDOC_FOUND)
 add_subdirectory(libibumad/man)
+endif()
 add_subdirectory(libibverbs)
+if (PANDOC_FOUND)
 add_subdirectory(libibverbs/man)
+endif()
 add_subdirectory(librdmacm)
+if (PANDOC_FOUND)
 add_subdirectory(librdmacm/man)
+endif()
 
 # Providers
 if (HAVE_COHERENT_DMA)
@@ -614,13 +620,19 @@
 add_subdirectory(providers/cxgb3) # NO SPARSE
 add_subdirectory(providers/cxgb4) # NO SPARSE
 add_subdirectory(providers/efa)
+if (PANDOC_FOUND)
 add_subdirectory(providers/efa/man)
+endif()
 add_subdirectory(providers/hns)
 add_subdirectory(providers/i40iw) # NO SPARSE
 add_subdirectory(providers/mlx4)
+if (PANDOC_FOUND)
 add_subdirectory(providers/mlx4/man)
+endif()
 add_subdirectory(providers/mlx5)
+if (PANDOC_FOUND)
 add_subdirectory(providers/mlx5/man)
+endif()
 add_subdirectory(providers/mthca)
 add_subdirectory(providers/nes) # NO SPARSE
 add_subdirectory(providers/ocrdma)
@@ -639,7 +651,9 @@
 add_subdirectory(libibnetdisc/man)
 add_subdirectory(infiniband-diags)
 add_subdirectory(infiniband-diags/scripts)
+if (PANDOC_FOUND)
 add_subdirectory(infiniband-diags/man)
+endif()
 
 if (CYTHON_EXECUTABLE)
   add_subdirectory(pyverbs)