HADOOP-11927. Fix "undefined reference to dlopen" error when compiling libhadooppipes (Xianyin Xin via Colin P. McCabe)

(cherry picked from commit f34638399abdca2e6d3bc5502508819dd747861c)

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -284,6 +284,9 @@ Release 2.8.0 - UNRELEASED
     HADOOP-11743. maven doesn't clean all the site files
     (ramtin via vinayakumarb)
 
+    HADOOP-11927.  Fix "undefined reference to dlopen" error when compiling
+    libhadooppipes (Xianyin Xin via Colin P. McCabe)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-tools/hadoop-pipes/src/CMakeLists.txt

@@ -69,7 +69,16 @@ add_library(hadooputils STATIC
 add_library(hadooppipes STATIC
     main/native/pipes/impl/HadoopPipes.cc
 )
+
+INCLUDE(CheckLibraryExists)
+CHECK_LIBRARY_EXISTS(dl dlopen "" NEED_LINK_DL)
+
+if (NEED_LINK_DL)
+    set(LIB_DL dl)
+endif (NEED_LINK_DL)
+
 target_link_libraries(hadooppipes
     ${OPENSSL_LIBRARIES}
+    ${LIB_DL}
     pthread
 )