Add source package to ${PACKAGES}

Permanently adds the -src source package to ${PACKAGES} instead of
relying on creating it dynamically at packaging time. The source package
is now defined in bitbake.conf, just like -dev and -dbg packages.

For compatibility, the -src package is still added dynamically if it was
missing, since some recipes have a tendency to completely override
PACKAGES and do so without manually adding back the -src package.

This allows RDEPENDS on the -src packages, which wasn't previously
possible.

[YOCTO #13203]

(From OE-Core rev: b25e1edf0204fc2f64aa8d66e09b8e2d67b90e17)

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/conf/bitbake.conf

@@ -237,6 +237,10 @@ DESCRIPTION ?= "${SUMMARY}."
 #SUMMARY_${PN} ?= "${SUMMARY}"
 #DESCRIPTION_${PN} ?= "${DESCRIPTION}"
 
+SUMMARY_${PN}-src ?= "${SUMMARY} - Source files"
+DESCRIPTION_${PN}-src ?= "${DESCRIPTION}  \
+This package contains sources for debugging purposes."
+
 SUMMARY_${PN}-dbg ?= "${SUMMARY} - Debugging files"
 DESCRIPTION_${PN}-dbg ?= "${DESCRIPTION}  \
 This package contains ELF symbols and related sources for debugging purposes."
@@ -285,7 +289,7 @@ SOLIBSDEV_darwin = ".dylibbroken"
 PACKAGE_DEBUG_SPLIT_STYLE ?= "debug-with-srcpkg"
 
 PACKAGE_BEFORE_PN ?= ""
-PACKAGES = "${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}"
+PACKAGES = "${PN}-src ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}"
 PACKAGES_DYNAMIC = "^${PN}-locale-.*"
 FILES = ""
 
@@ -324,6 +328,11 @@ FILES_${PN}-dbg = "/usr/lib/debug /usr/src/debug"
 SECTION_${PN}-dbg = "devel"
 ALLOW_EMPTY_${PN}-dbg = "1"
 
+# The files list for source packages are dynamically set based on
+# PACKAGE_DEBUG_SPLIT_STYLE
+FILES_${PN}-src = ""
+SECTION_${PN}-src = "devel"
+
 FILES_${PN}-locale = "${datadir}/locale"
 
 # File manifest