[Package: HPX] Fix Apex and OTF2 support (#13982)

* Fix Apex and OTF2 support

- Comment out apex as a dependncy: it is bundled with HPX.
- Apply a patch to v1.3.0 to correctly build with APEX.
- Add otf2 as a dependency when APEX is enabled.

* Remove depends_on('apex')

var/spack/repos/builtin/packages/hpx/git_external.patch

@@ -0,0 +1,81 @@
+--- hpx/cmake/GitExternal.cmake.orig	2019-08-16 17:27:04.856315000 +0200
++++ hpx/cmake/GitExternal.cmake	2019-08-16 17:27:47.362709000 +0200
+@@ -19,12 +19,12 @@
+ #
+ # [optional] Flags which control behaviour
+ #  NO_UPDATE
+-#    When set, GitExternal will not change a repo that has already been checked out. 
+-#    The purpose of this is to allow one to set a default branch to be checked out, 
+-#    but stop GitExternal from changing back to that branch if the user has checked 
++#    When set, GitExternal will not change a repo that has already been checked out.
++#    The purpose of this is to allow one to set a default branch to be checked out,
++#    but stop GitExternal from changing back to that branch if the user has checked
+ #    out and is working on another.
+-#  VERBOSE 
+-#    When set, displays information about git commands that are executed  
++#  VERBOSE
++#    When set, displays information about git commands that are executed
+ #
+ 
+ find_package(Git)
+@@ -55,17 +55,21 @@
+     if(nok)
+       message(FATAL_ERROR "${DIR} git clone failed: ${error}\n")
+     endif()
+-  endif()
+ 
+-  if(IS_DIRECTORY "${DIR}/.git")
++    # checkout requested tag
++    GIT_EXTERNAL_MESSAGE("git checkout -q ${TAG}")
++    execute_process(
++      COMMAND "${GIT_EXECUTABLE}" checkout -q "${TAG}"
++      RESULT_VARIABLE nok ERROR_VARIABLE error
++      WORKING_DIRECTORY "${DIR}"
++      )
++    if(nok)
++      message(STATUS "${DIR} git checkout ${TAG} failed: ${error}\n")
++    endif()
++  elseif(IS_DIRECTORY "${DIR}/.git")
+     if (${GIT_EXTERNAL_NO_UPDATE})
+       GIT_EXTERNAL_MESSAGE("Update branch disabled by user")
+     else()
+-      GIT_EXTERNAL_MESSAGE("current ref is \"${currentref}\" and tag is \"${TAG}\"")
+-      if(currentref STREQUAL TAG) # nothing to do
+-        return()
+-      endif()
+-
+       # reset generated files
+       foreach(GIT_EXTERNAL_RESET_FILE ${GIT_EXTERNAL_RESET})
+         GIT_EXTERNAL_MESSAGE("git reset -q ${GIT_EXTERNAL_RESET_FILE}")
+@@ -100,15 +104,24 @@
+         message(STATUS "${DIR} git checkout ${TAG} failed: ${error}\n")
+       endif()
+ 
+-      # update tag
+-      GIT_EXTERNAL_MESSAGE("git rebase FETCH_HEAD")
+-      execute_process(COMMAND ${GIT_EXECUTABLE} rebase FETCH_HEAD
+-        RESULT_VARIABLE RESULT OUTPUT_VARIABLE OUTPUT ERROR_VARIABLE OUTPUT
++      # check if this is a branch
++      GIT_EXTERNAL_MESSAGE("git symbolic-ref -q HEAD")
++      execute_process(COMMAND "${GIT_EXECUTABLE}" symbolic-ref -q HEAD
++        RESULT_VARIABLE nok ERROR_VARIABLE error
+         WORKING_DIRECTORY "${DIR}")
+-      if(RESULT)
+-        message(STATUS "git rebase failed, aborting ${DIR} merge")
+-        execute_process(COMMAND ${GIT_EXECUTABLE} rebase --abort
++      if(nok)
++        message(STATUS "${TAG} is not a branch")
++      else()
++        # update tag
++        GIT_EXTERNAL_MESSAGE("git rebase FETCH_HEAD")
++        execute_process(COMMAND ${GIT_EXECUTABLE} rebase FETCH_HEAD
++          RESULT_VARIABLE RESULT OUTPUT_VARIABLE OUTPUT ERROR_VARIABLE OUTPUT
+           WORKING_DIRECTORY "${DIR}")
++        if(RESULT)
++          message(STATUS "git rebase failed, aborting ${DIR} merge")
++          execute_process(COMMAND ${GIT_EXECUTABLE} rebase --abort
++            WORKING_DIRECTORY "${DIR}")
++        endif()
+       endif()
+     endif()
+   else()

var/spack/repos/builtin/packages/hpx/package.py

@@ -76,11 +76,14 @@ class Hpx(CMakePackage, CudaPackage):
     depends_on('mpi', when='networking=mpi')
 
     # Instrumentation
-    depends_on('apex', when='instrumentation=apex')
+    depends_on('otf2', when='instrumentation=apex')
     depends_on('gperftools', when='instrumentation=google_perftools')
     depends_on('papi', when='instrumentation=papi')
     depends_on('valgrind', when='instrumentation=valgrind')
 
+    # Patches APEX
+    patch('git_external.patch', when='@1.3.0 instrumentation=apex')
+
     def cxx_standard(self):
         value = self.spec.variants['cxxstd'].value
         return '-DHPX_WITH_CXX{0}=ON'.format(value)
@@ -108,6 +111,10 @@ def cmake_args(self):
         # Instrumentation
         args.extend(self.instrumentation_args())
 
+        if 'instrumentation=apex' in spec:
+            args += ['-DAPEX_WITH_OTF2=ON'
+                     '-DOTF2_ROOT={0}'.format(spec['otf2'].prefix)]
+
         # Networking
         args.append('-DHPX_WITH_NETWORKING={0}'.format(
             'OFF' if 'networking=none' in spec else 'ON'