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.

Author: ruevs

src/CMakeLists.txt

@@ -23,15 +23,13 @@ target_include_directories(slvs_deps SYSTEM INTERFACE
     ${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 SYSTEM INTERFACE

src/slvs/CMakeLists.txt

@@ -5,7 +5,7 @@ add_library(slvs-interface INTERFACE)
 target_sources(slvs-interface INTERFACE lib.cpp)
 target_compile_definitions(slvs-interface INTERFACE -DLIBRARY)
 target_include_directories(slvs-interface INTERFACE ${CMAKE_SOURCE_DIR}/include)
-target_link_libraries(slvs-interface INTERFACE slvs-solver mimalloc-static)
+target_link_libraries(slvs-interface INTERFACE slvs-solver)
 
 if(ENABLE_PYTHON_LIB)
     add_custom_command(