pkg/codesearch: add skeleton for code searching tool

Add a clang tool that is used for code indexing (tools/clang/codesearch/).
It follows conventions and build procedure of the declextract tool.

Add pkg/codesearch package that aggregates the info exposed by the clang tools,
and allows doing simple queries:
 - show source code of an entity (function, struct, etc)
 - show entity comment
 - show all entities defined in a source file

Add tools/syz-codesearch wrapper tool that allows to create index for a kernel build,
and then run code queries on it.

1 files changed, 8 insertions, 0 deletions

diff --git a/pkg/codesearch/testdata/query-def-source-same-name-static b/pkg/codesearch/testdata/query-def-source-same-name-static
new file mode 100644
index 000000000..3d87c010c
--- /dev/null
+++ b/pkg/codesearch/testdata/query-def-source-same-name-static
@@ -0,0 +1,8 @@
+def-source source1.c same_name_in_several_files yes
+
+function same_name_in_several_files is defined in source1.c:
+
+   3:	static void same_name_in_several_files()
+   4:	{
+   5:		// This is static version in source1.c.
+   6:	}