Bug 3792

When Adding "dev-pkgs" feature to IMAGE_FEATURE many development packages are not installed in the final rootfs

STEPS TO REPRODUCE:
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1.select packageXX and check that it provides packageXX-dev
2.set IMAGE_INSTAL+="packageXX"
3.set IMAGE_FEATURES+="dev-pkgs"
3.build the image using bitbake (bitbake my-image) 
4.check that files installed by packageXX-dev are not present in the generated rootfs

CAUSE :
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* To install complementary packages (dev, staticdev, doc ...) the script oe-pkgdata-util is called during rootfs generation. This script takes a file containing  all installed packages (installed_packages.txt) and computes the set of complementary packages to install (depending on what is contained in IMAGE_FEATURES). 

* Actually installed_packages.txt is a two columns file containing the package name and the architecture of the package, architecture of the package uses underscore as separator (ex : armv7a_vfp_neon).

* oe-pkgdata-util uses the architecture of a each package (from installed_packages.txt) to rebuilt the full path to packages data in order to check if it actually provides dev-pkgs, static-dev ...etc. (ex: build/tmp-eglibc/pkgdata/armv7a_vfp_neon-oe-linux-gnueabi)

* in the pkgdata directory  packages are grouped by their architecture in separate directories, but the directories name use dash as separator (ex: build/tmp-eglibc/pkgdata/armv7a-vfp-neon-oe-linux-gnueabi)

* due to the difference of the separator on the path reconstructed by   oe-pkgdata-util and the  path of pkgdata, oe-pkgdata-util  will miss the  installation of many packages.