Long live qbs-pkgconfig!

This patchset introduce a static library for parsing .pc files. Code is
based on the original pkg-config source code https://
gitlab.freedesktop.org/pkg-config/pkg-config and is written in pure C++
(except for the places where we need access to filesystem as
std::filesystem is not available for all platforms - in that case, Qt
classes are used)

Parsing .pc files manually allows to have more control over dependencies
between modules, e.g. to generate a standalone module per one .pc file
and merge properties using Qbs itself, not via pkg-config.

Library is almost feature-complete and all tests copied from pkg-config
pass. Some functionality is omitted (e.g. prefix variables (what is
this?) or validating dependencies since Qbs does this as well)

Bechmark shows that parsing ~100 files takes about 10-15ms. Running
pkg-config on the same set of files takes ~4 seconds:

RESULT : TestPkgConfig::benchSystem():
     14 msecs per iteration (total: 57, iterations: 4)

Fixes: QBS-1615
Change-Id: I5bfdfa588aa04d9d69fd738dd2beea14174c0242
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/lib/libs.qbs b/src/lib/libs.qbs
index 264036e1a..10890bb46 100644
--- a/src/lib/libs.qbs
+++ b/src/lib/libs.qbs
@@ -2,6 +2,7 @@ Project {
     references: [
         "corelib/corelib.qbs",
         "msbuild/msbuild.qbs",
+        "pkgconfig/pkgconfig.qbs",
         "scriptengine/scriptengine.qbs",
     ]
 }