Unify the colorspace on macOS/watchOS choosen for draw to use sRGB firstly

Remove the unused OS version check

SDWebImage/Core/SDImageCoderHelper.m

@@ -189,24 +189,10 @@ static const CGFloat kDestSeemOverlap = 2.0f;   // the numbers of pixels to over
 }
 
 + (CGColorSpaceRef)colorSpaceGetDeviceRGB {
-#if SD_MAC
-    CGColorSpaceRef screenColorSpace = NSScreen.mainScreen.colorSpace.CGColorSpace;
-    if (screenColorSpace) {
-        return screenColorSpace;
-    }
-#endif
     static CGColorSpaceRef colorSpace;
     static dispatch_once_t onceToken;
     dispatch_once(&onceToken, ^{
-#if SD_UIKIT
-        if (@available(iOS 9.0, tvOS 9.0, *)) {
         colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceSRGB);
-        } else {
-            colorSpace = CGColorSpaceCreateDeviceRGB();
-        }
-#else
-        colorSpace = CGColorSpaceCreateDeviceRGB();
-#endif
     });
     return colorSpace;
 }

SDWebImage/Core/SDImageGraphics.m

@@ -8,6 +8,7 @@
 
 #import "SDImageGraphics.h"
 #import "NSImage+Compatibility.h"
+#import "SDImageCoderHelper.h"
 #import "objc/runtime.h"
 
 #if SD_MAC
@@ -22,7 +23,7 @@ static CGContextRef SDCGContextCreateBitmapContext(CGSize size, BOOL opaque, CGF
     size_t height = ceil(size.height * scale);
     if (width < 1 || height < 1) return NULL;
     
-    CGColorSpaceRef space = NSScreen.mainScreen.colorSpace.CGColorSpace;
+    CGColorSpaceRef space = [SDImageCoderHelper colorSpaceGetDeviceRGB];
     // kCGImageAlphaNone is not supported in CGBitmapContextCreate.
     // Check #3330 for more detail about why this bitmap is choosen.
     CGBitmapInfo bitmapInfo;