hpx: remove unused patch file (#50463)

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

@@ -1,81 +0,0 @@
---- 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()