Build: Fix build/install with Xcode IDE

Closes #355
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9f63406..ce04d55 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -536,7 +536,7 @@
 endif()
 if(WITH_SIMD)
   message(STATUS "SIMD extensions: ${CPU_TYPE} (WITH_SIMD = ${WITH_SIMD})")
-  if(MSVC_IDE)
+  if(MSVC_IDE OR XCODE)
     set_source_files_properties(${SIMD_OBJS} PROPERTIES GENERATED 1)
   endif()
 else()
@@ -666,7 +666,7 @@
 
 add_subdirectory(md5)
 
-if(MSVC_IDE)
+if(MSVC_IDE OR XCODE)
   set(OBJDIR "\${CTEST_CONFIGURATION_TYPE}/")
 else()
   set(OBJDIR "")
@@ -1342,7 +1342,7 @@
     install(TARGETS turbojpeg-static ARCHIVE
       DESTINATION ${CMAKE_INSTALL_LIBDIR})
     if(NOT ENABLE_SHARED)
-      if(MSVC_IDE)
+      if(MSVC_IDE OR XCODE)
         set(DIR "${CMAKE_CURRENT_BINARY_DIR}/\${CMAKE_INSTALL_CONFIG_NAME}")
       else()
         set(DIR ${CMAKE_CURRENT_BINARY_DIR})
@@ -1358,7 +1358,7 @@
 if(ENABLE_STATIC)
   install(TARGETS jpeg-static ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
   if(NOT ENABLE_SHARED)
-    if(MSVC_IDE)
+    if(MSVC_IDE OR XCODE)
       set(DIR "${CMAKE_CURRENT_BINARY_DIR}/\${CMAKE_INSTALL_CONFIG_NAME}")
     else()
       set(DIR ${CMAKE_CURRENT_BINARY_DIR})
diff --git a/sharedlib/CMakeLists.txt b/sharedlib/CMakeLists.txt
index a5c4e39..8d65e58 100755
--- a/sharedlib/CMakeLists.txt
+++ b/sharedlib/CMakeLists.txt
@@ -23,7 +23,7 @@
   set(JPEG_SRCS ${JPEG_SRCS} ../${src})
 endforeach()
 
-if(WITH_SIMD AND MSVC_IDE)
+if(WITH_SIMD AND (MSVC_IDE OR XCODE))
   # This tells CMake that the "source" files haven't been generated yet
   set_source_files_properties(${SIMD_OBJS} PROPERTIES GENERATED 1)
 endif()
diff --git a/simd/CMakeLists.txt b/simd/CMakeLists.txt
index 8dbd7f1..3472c0d 100755
--- a/simd/CMakeLists.txt
+++ b/simd/CMakeLists.txt
@@ -135,6 +135,9 @@
 if(MSVC_IDE)
   set(OBJDIR "${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}")
   string(REGEX REPLACE " " ";" CMAKE_ASM_NASM_FLAGS "${CMAKE_ASM_NASM_FLAGS}")
+elseif(XCODE)
+  set(OBJDIR "${CMAKE_CURRENT_BINARY_DIR}")
+  string(REGEX REPLACE " " ";" CMAKE_ASM_NASM_FLAGS "${CMAKE_ASM_NASM_FLAGS}")
 endif()
 
 file(GLOB INC_FILES nasm/*.inc)
@@ -162,13 +165,13 @@
       ${CMAKE_CURRENT_SOURCE_DIR}/${DEPFILE})
   endif()
   set(OBJECT_DEPENDS ${OBJECT_DEPENDS} ${INC_FILES})
-  if(MSVC_IDE)
+  if(MSVC_IDE OR XCODE)
     # The CMake Visual Studio generators do not work properly with the ASM_NASM
     # language, so we have to go rogue here and use a custom command like we
     # did in prior versions of libjpeg-turbo.  (This is why we can't have nice
     # things.)
     string(REGEX REPLACE "${CPU_TYPE}/" "" filename ${file})
-    set(SIMD_OBJ ${OBJDIR}/${filename}.obj)
+    set(SIMD_OBJ ${OBJDIR}/${filename}${CMAKE_C_OUTPUT_EXTENSION})
     add_custom_command(OUTPUT ${SIMD_OBJ} DEPENDS ${file} ${OBJECT_DEPENDS}
       COMMAND ${CMAKE_ASM_NASM_COMPILER} -f${CMAKE_ASM_NASM_OBJECT_FORMAT}
         ${CMAKE_ASM_NASM_FLAGS} ${CMAKE_CURRENT_SOURCE_DIR}/${file}
@@ -180,7 +183,7 @@
   endif()
 endforeach()
 
-if(MSVC_IDE)
+if(MSVC_IDE OR XCODE)
   set(SIMD_OBJS ${SIMD_OBJS} PARENT_SCOPE)
   add_library(simd OBJECT ${CPU_TYPE}/jsimd.c)
   add_custom_target(simd-objs DEPENDS ${SIMD_OBJS})