rules: Refactoring and minor improvements

Compared to the previous commit, the action graphs for just
and its unit tests are unchanged.
- Git hash of action graph for ["",""]:
    c6e75f17abd7ffaab6ff9bb725ad67ec0bf6c973
- Git hash of action graph for ["test/buildtool","TESTS"]:
    8063dfb3dd7daa9ae01d95c177e14946f785c57e

Refactor:
- "local cflags" to "private-cflags"
- "local defines" to "private-defines"
- "link externals" to "private-ldflags"
- "deps" to "private-deps" for (test) binaries
- "proto" to "private-proto" for binaries

Improvements:
- consistent variable declaration order:
    OS, ARCH, HOST_ARCH, TARGET_ARCH,
    CC, CXX, CFLAGS, CXXFLAGS, ADD_CFLAGS, ADD_CXXFLAGS,
    AR, ENV, PATH
- use fields close to their definition (in RULES)
- use common expression for binaries and test binaries
- split expression "flags" and "compiler"
  ... to separate ones for CC and CXX.
- rename "transition" to "deps-transition"
  ... to avoid conflicts with other transitions.
- support "defaults-transition" for CC expressions

Implement:
- "cflags" for libraries
- "private-cflags" for (test) binaries
- "private-defines" for test binaries
- "private-ldflags" for test binaries
- (public) "defines" for libraries

1 files changed, 2 insertions, 2 deletions

diff --git a/test/buildtool/graph_traverser/TARGETS b/test/buildtool/graph_traverser/TARGETS
index cf47ff26..302c68e0 100644
--- a/test/buildtool/graph_traverser/TARGETS
+++ b/test/buildtool/graph_traverser/TARGETS
@@ -17,7 +17,7 @@
   , "name": ["graph_traverser_local"]
   , "srcs": ["graph_traverser_local.test.cpp"]
   , "data": ["test_data"]
-  , "deps":
+  , "private-deps":
     [ "graph_traverser_tests"
     , ["@", "catch2", "", "catch2"]
     , ["test", "catch-main"]
@@ -30,7 +30,7 @@
   , "name": ["graph_traverser_remote"]
   , "srcs": ["graph_traverser_remote.test.cpp"]
   , "data": ["test_data"]
-  , "deps":
+  , "private-deps":
     [ "graph_traverser_tests"
     , ["@", "catch2", "", "catch2"]
     , ["test/utils", "catch-main-remote-execution"]