Use `find_package(JPEG)` in place of `include(FindJPEG)`

The former allows the package to be overridden with a local build by
`FetchContent`.

Also includes the fix to _MSC_VER conditions from:
https://aomedia.googlesource.com/aom/+/refs/heads/main/third_party/libyuv/README.libaom

Change-Id: I666e591becb3efaa7b5b68d27476319a2909b88e
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/3933570
Reviewed-by: Wan-Teh Chang <wtc@google.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index d190507..5f0306b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -42,7 +42,7 @@
 TARGET_LINK_LIBRARIES	( yuvconvert ${ly_lib_static} )
 
 
-INCLUDE ( FindJPEG )
+find_package ( JPEG )
 if (JPEG_FOUND)
   include_directories( ${JPEG_INCLUDE_DIR} )
   target_link_libraries( yuvconvert ${JPEG_LIBRARY} )
diff --git a/source/cpu_id.cc b/source/cpu_id.cc
index 7467c5d..13e3da7 100644
--- a/source/cpu_id.cc
+++ b/source/cpu_id.cc
@@ -108,7 +108,7 @@
 //  }
 // For VS2013 and earlier 32 bit, the _xgetbv(0) optimizer produces bad code.
 // https://code.google.com/p/libyuv/issues/detail?id=529
-#if defined(_M_IX86) && (_MSC_VER < 1900)
+#if defined(_M_IX86) && defined(_MSC_VER) && (_MSC_VER < 1900)
 #pragma optimize("g", off)
 #endif
 #if (defined(_M_IX86) || defined(_M_X64) || defined(__i386__) || \
@@ -129,7 +129,7 @@
 #define GetXCR0() 0
 #endif  // defined(_M_IX86) || defined(_M_X64) ..
 // Return optimization to previous setting.
-#if defined(_M_IX86) && (_MSC_VER < 1900)
+#if defined(_M_IX86) && defined(_MSC_VER) && (_MSC_VER < 1900)
 #pragma optimize("g", on)
 #endif