package/jpeg: make it behave more like other virtual packages

Currently, the virtual package jpeg is a special virtual package,
as it offers a choice for its implementation, rather than letting the
user enable them manually.

In so doing, it defines its _HAS option as a 'def_bool y' rather than
letting each implementation 'select' it.

Since we are going to generate a list of virtual packages and their
providers, this defeats the heuristic used to find providers.

Coming with an alternate heuristic that also matches the jpeg
package is quite complex, so better and easier to make it look more
like any other virtual package.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Samuel Martin <s.martin49@gmail.com>
Reviewed-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/jpeg/Config.in

@@ -13,6 +13,7 @@ choice
 
 config BR2_PACKAGE_LIBJPEG
 	bool "jpeg"
+	select BR2_PACKAGE_HAS_JPEG
 	help
 	  The ubiquitous C library for manipulating JPEG images.
 
@@ -20,6 +21,7 @@ config BR2_PACKAGE_LIBJPEG
 
 config BR2_PACKAGE_JPEG_TURBO
 	bool "jpeg-turbo"
+	select BR2_PACKAGE_HAS_JPEG
 	help
 	  Libjpeg-turbo is a derivative of libjpeg that uses SIMD
 	  instructions (MMX, SSE2, NEON) to accelerate baseline JPEG
@@ -31,7 +33,7 @@ config BR2_PACKAGE_JPEG_TURBO
 endchoice
 
 config BR2_PACKAGE_HAS_JPEG
-	def_bool y
+	bool
 
 config BR2_PACKAGE_PROVIDES_JPEG
 	string