[RFC][debuginfo-test] Rename debug-info lit tests for general purposes

Discussion thread:
https://lists.llvm.org/pipermail/llvm-dev/2021-January/148048.html

Move debuginfo-test into a subdirectory of a new top-level directory,
called cross-project-tests. The new name replaces "debuginfo-test" as an
LLVM project enabled via LLVM_ENABLE_PROJECTS.

Differential Revision: https://reviews.llvm.org/D95339

Reviewed by: aprantl

README.md

@@ -66,7 +66,7 @@ This is an example work-flow and configuration to get and build the LLVM source:
         * ``-DLLVM_ENABLE_PROJECTS='...'`` --- semicolon-separated list of the LLVM
           sub-projects you'd like to additionally build. Can include any of: clang,
           clang-tools-extra, libcxx, libcxxabi, libunwind, lldb, compiler-rt, lld,
-          polly, or debuginfo-tests.
+          polly, or cross-project-tests.
 
           For example, to build LLVM, Clang, libcxx, and libcxxabi, use
           ``-DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi"``.

cross-project-tests/CMakeLists.txt

@@ -5,7 +5,7 @@
 find_package(Python3 COMPONENTS Interpreter)
 
 add_llvm_executable(check-gdb-llvm-support
-        llvm-prettyprinters/gdb/llvm-support.cpp
+        debuginfo-tests/llvm-prettyprinters/gdb/llvm-support.cpp
 )
 target_link_libraries(check-gdb-llvm-support PRIVATE LLVMSupport)
 
@@ -24,7 +24,7 @@ set(DEBUGINFO_TEST_DEPS
 
 if ("mlir" IN_LIST LLVM_ENABLE_PROJECTS)
   add_llvm_executable(check-gdb-mlir-support
-        llvm-prettyprinters/gdb/mlir-support.cpp
+        debuginfo-tests/llvm-prettyprinters/gdb/mlir-support.cpp
   )
   target_include_directories(check-gdb-mlir-support PRIVATE
                                ${LLVM_EXTERNAL_MLIR_SOURCE_DIR}/include
@@ -61,7 +61,7 @@ configure_lit_site_cfg(
   ${CMAKE_CURRENT_SOURCE_DIR}/lit.cfg.py
   )
 
-add_lit_testsuite(check-debuginfo "Running debug info integration tests"
+add_lit_testsuite(check-debuginfo "Running cross-project tests"
   ${CMAKE_CURRENT_BINARY_DIR}
   DEPENDS ${DEBUGINFO_TEST_DEPS}
   )
@@ -71,4 +71,4 @@ add_lit_testsuites(DEBUGINFO ${CMAKE_CURRENT_SOURCE_DIR}
   DEPENDS ${DEBUGINFO_TEST_DEPS}
   )
 
-set_target_properties(check-debuginfo PROPERTIES FOLDER "Debug info tests")
+set_target_properties(check-debuginfo PROPERTIES FOLDER "Tests")