Fix RUN_GTEST/RUN_GBENCH leak into pax.so build

ADD_DEFINITIONS(-DRUN_GTEST) and ADD_DEFINITIONS(-DRUN_GBENCH)
are directory-scoped CMake commands that apply to ALL targets,
including the production pax shared library. This caused test-
only macros to be defined in production builds.

In pax_porc_adpater.cc, the leaked RUN_GTEST activates:

    expect_hdr = rel_tuple_desc_->attrs[index].attlen == -1 &&
                 rel_tuple_desc_->attrs[index].attbyval == false;

    #ifdef RUN_GTEST
    expect_hdr = false;
    #endif

This forces expect_hdr to false in production, skipping the
stripping of PostgreSQL varlena headers from dictionary
entries. As a result, dictionary-encoded string columns
return garbled data (varlena header bytes are included as
part of the string content).

Replace ADD_DEFINITIONS with target_compile_definitions
scoped to test_main and bench_main targets only, so
RUN_GTEST and RUN_GBENCH are no longer defined when
building pax.so.

Author: zhangyue1818

contrib/pax_storage/src/cpp/cmake/pax.cmake

@@ -223,14 +223,14 @@ add_custom_command(TARGET pax POST_BUILD
 
 if (BUILD_GTEST)
   add_subdirectory(contrib/googletest)
-  ADD_DEFINITIONS(-DRUN_GTEST)
   file(GLOB test_case_sources
     pax_gtest_helper.cc
     pax_gtest.cc
     ${CMAKE_CURRENT_SOURCE_DIR}/*/*_test.cc
     ${CMAKE_CURRENT_SOURCE_DIR}/*/*/*_test.cc)
 
   add_executable(test_main ${pax_target_src} ${test_case_sources})
+  target_compile_definitions(test_main PRIVATE RUN_GTEST)
   add_dependencies(test_main ${pax_target_dependencies} gtest gmock)
   target_include_directories(test_main PUBLIC ${pax_target_include} ${CMAKE_CURRENT_SOURCE_DIR} ${gtest_SOURCE_DIR}/include contrib/cpp-stub/src/ contrib/cpp-stub/src_linux/)
 
@@ -240,13 +240,13 @@ endif(BUILD_GTEST)
 
 if(BUILD_GBENCH)
   add_subdirectory(contrib/googlebench)
-  ADD_DEFINITIONS(-DRUN_GBENCH)
   file(GLOB bench_sources
       pax_gbench.cc
       ${CMAKE_CURRENT_SOURCE_DIR}/*/*_bench.cc
       ${CMAKE_CURRENT_SOURCE_DIR}/*/*/*_bench.cc)
 
     add_executable(bench_main ${pax_target_src} ${bench_sources})
+    target_compile_definitions(bench_main PRIVATE RUN_GBENCH)
     add_dependencies(bench_main ${pax_target_dependencies} gtest gmock)
     target_include_directories(bench_main PUBLIC ${pax_target_include} ${CMAKE_CURRENT_SOURCE_DIR} contrib/googlebench/include contrib/cpp-stub/src/ contrib/cpp-stub/src_linux/)
     link_directories(contrib/googlebench/src)