Introduce libosmocore_git.bbappend to fix TLS bug

Related: OS#5079

recipes-sysmobts/libosmocore/libosmocore_git.bbappend

@@ -0,0 +1,10 @@
+# OS#4062, OS#5079: When building with sysmobts toolchain we hit a TLS compiler
+# bug (osmo-bts-symo calling osmo_str_tolower() which uses "static __thread char
+# capsbuf"). As a result, the only option would be to use -O0 when building
+# libosmocore. In order to avoid that, we take advantage of the fact that no
+# libosmocore multi-thread process is expected to run there and simply drop all
+# the "__thread" references when building for sysmobts. That's done as a
+# machine-specific bbappend in meta-sysmocom-bsp.
+do_compile_prepend() {
+        grep -r -l "__thread" "${S}/src/" "${S}/include/" | xargs sed -i "s/__thread//g"
+}