toolchain-external: mass-define actual source tarball for known patterns

For some external toolchain vendors the actual source code URL can be simply
derived from the binary file URL.

Here we obtain TOOLCHAIN_EXTERNAL_ACTUAL_SOURCE_TARBALL for all Mentor and
Linaro toolchains with a few $(subst) calls.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Cc: Thomas De Schampheleire <patrickdepinguin@gmail.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

toolchain/toolchain-external/toolchain-external.mk

@@ -418,6 +418,16 @@ TOOLCHAIN_EXTERNAL_SOURCE = $(notdir $(call qstrip,$(BR2_TOOLCHAIN_EXTERNAL_URL)
 BR_NO_CHECK_HASH_FOR += $(TOOLCHAIN_EXTERNAL_SOURCE)
 endif
 
+# Some toolchain vendors have a regular file naming pattern.
+# For them, mass-define _ACTUAL_SOURCE_TARBALL based _SITE.
+ifneq ($(findstring sourcery.mentor.com/public/gnu_toolchain,$(TOOLCHAIN_EXTERNAL_SITE)),)
+TOOLCHAIN_EXTERNAL_ACTUAL_SOURCE_TARBALL ?= \
+	$(subst -i686-pc-linux-gnu.tar.bz2,.src.tar.bz2,$(subst -i686-pc-linux-gnu-i386-linux.tar.bz2,-i686-pc-linux-gnu.src.tar.bz2,$(TOOLCHAIN_EXTERNAL_SOURCE)))
+else ifneq ($(findstring http://releases.linaro.org,$(TOOLCHAIN_EXTERNAL_SITE)),)
+TOOLCHAIN_EXTERNAL_ACTUAL_SOURCE_TARBALL ?= \
+	$(subst _linux.tar.xz,_src.tar.bz2,$(TOOLCHAIN_EXTERNAL_SOURCE))
+endif
+
 # In fact, we don't need to download the toolchain, since it is already
 # available on the system, so force the site and source to be empty so
 # that nothing will be downloaded/extracted.