Remove support for using jemalloc instead of the system allocator

There was never any investigation done to determine whether using
jemalloc was actually a net benefit for nvim.  It has been a portability
limitation and adds another factor to consider when triaging issues.

third-party/CMakeLists.txt

@@ -30,7 +30,6 @@ set(DEPS_DOWNLOAD_DIR "${DEPS_BUILD_DIR}/downloads" CACHE PATH "Dependencies dow
 option(USE_BUNDLED "Use bundled dependencies." ON)
 
 option(USE_BUNDLED_GPERF "Use the bundled version of gperf." ${USE_BUNDLED})
-option(USE_BUNDLED_JEMALLOC "Use the bundled jemalloc." ${USE_BUNDLED})
 option(USE_BUNDLED_UNIBILIUM "Use the bundled unibilium." ${USE_BUNDLED})
 option(USE_BUNDLED_LIBTERMKEY "Use the bundled libtermkey." ${USE_BUNDLED})
 option(USE_BUNDLED_LIBVTERM "Use the bundled libvterm." ${USE_BUNDLED})
@@ -150,9 +149,6 @@ set(LIBTERMKEY_SHA256 6c0d87c94ab9915e76ecd313baec08dedf3bd56de83743d9aa923a0819
 set(LIBVTERM_URL https://github.com/neovim/libvterm/archive/3f62ac6b7bdffda39d68f723fb1806dfd6d6382d.tar.gz)
 set(LIBVTERM_SHA256 1c8b318370f00f831f43e3ec86a48984250e3ee5c76beb106a421c9a42286ac5)
 
-set(JEMALLOC_URL https://github.com/jemalloc/jemalloc/releases/download/4.5.0/jemalloc-4.5.0.tar.bz2)
-set(JEMALLOC_SHA256 9409d85664b4f135b77518b0b118c549009dc10f6cba14557d170476611f6780)
-
 set(LUV_URL https://github.com/luvit/luv/archive/1.9.1-1.tar.gz)
 set(LUV_SHA256 562b9efaad30aa051a40eac9ade0c3df48bb8186763769abe47ec3fb3edb1268)
 
@@ -212,10 +208,6 @@ if(USE_BUNDLED_LUAROCKS)
   include(BuildLuarocks)
 endif()
 
-if(USE_BUNDLED_JEMALLOC)
-  include(BuildJeMalloc)
-endif()
-
 if(USE_BUNDLED_LUV)
   include(BuildLuv)
 endif()

third-party/cmake/BuildJeMalloc.cmake

@@ -1,24 +0,0 @@
-if(WIN32)
-  message(STATUS "Building jemalloc in Windows is not supported (skipping)")
-  return()
-endif()
-
-ExternalProject_Add(jemalloc
-  PREFIX ${DEPS_BUILD_DIR}
-  URL ${JEMALLOC_URL}
-  DOWNLOAD_DIR ${DEPS_DOWNLOAD_DIR}/jemalloc
-  DOWNLOAD_COMMAND ${CMAKE_COMMAND}
-    -DPREFIX=${DEPS_BUILD_DIR}
-    -DDOWNLOAD_DIR=${DEPS_DOWNLOAD_DIR}/jemalloc
-    -DURL=${JEMALLOC_URL}
-    -DEXPECTED_SHA256=${JEMALLOC_SHA256}
-    -DTARGET=jemalloc
-    -DUSE_EXISTING_SRC_DIR=${USE_EXISTING_SRC_DIR}
-    -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/DownloadAndExtractFile.cmake
-  BUILD_IN_SOURCE 1
-  CONFIGURE_COMMAND ${DEPS_BUILD_DIR}/src/jemalloc/configure
-     CC=${DEPS_C_COMPILER} --prefix=${DEPS_INSTALL_DIR}
-  BUILD_COMMAND ""
-  INSTALL_COMMAND ${MAKE_PRG} install_include install_lib_static)
-
-list(APPEND THIRD_PARTY_DEPS jemalloc)