Revert "Add and build mimalloc at 07c..."

This reverts commit cbac182

Removing the `mimalloc` dependency will make it easier to build
Windows XP (maybe even 2000) compatible versions of SolveSpace.

CMakeLists.txt

@@ -193,14 +193,6 @@ endif()
 message(STATUS "Using in-tree libdxfrw")
 add_subdirectory(extlib/libdxfrw)
 
-message(STATUS "Using in-tree mimalloc")
-set(MI_OVERRIDE OFF CACHE BOOL "")
-set(MI_BUILD_SHARED OFF CACHE BOOL "")
-set(MI_BUILD_OBJECT OFF CACHE BOOL "")
-set(MI_BUILD_TESTS OFF CACHE BOOL "")
-add_subdirectory(extlib/mimalloc EXCLUDE_FROM_ALL)
-set(MIMALLOC_INCLUDE_DIR ${CMAKE_SOURCE_DIR}/extlib/mimalloc/include)
-
 if(NOT FORCE_VENDORED_Eigen3)
     find_package(Eigen3 CONFIG)
 endif()

src/CMakeLists.txt

@@ -27,15 +27,13 @@ target_include_directories(slvs_deps INTERFACE SYSTEM
     ${PNG_PNG_INCLUDE_DIR}
     ${FREETYPE_INCLUDE_DIRS}
     ${CAIRO_INCLUDE_DIRS}
-    ${MIMALLOC_INCLUDE_DIR}
     ${EIGEN3_INCLUDE_DIRS})
 target_link_libraries(slvs_deps INTERFACE
     dxfrw
     ${ZLIB_LIBRARY}
     ${PNG_LIBRARY}
     ${FREETYPE_LIBRARY}
-    ${CAIRO_LIBRARIES}
-    mimalloc-static)
+    ${CAIRO_LIBRARIES})
 
 if(Backtrace_FOUND)
     target_include_directories(slvs_deps INTERFACE SYSTEM