Fix: ELPA test compile (#3774)

* include genelpa header instead seperate header for elpa test

* fix "\'gtest/gtest.h\' not found"

* add my_elpa back to pass compile.
It is strange that using standard c++ header <complex>(from elpa/elpa.h) instead of <complex.h>(in module_hsolver/my_elpa.h) would cause compile error.

* old elpa compatibility macros

source/module_hamilt_lcao/module_tddft/test/CMakeLists.txt

@@ -1,6 +1,8 @@
 remove_definitions(-D __MPI)
 
 add_library(tddft_test_lib tddft_test.cpp)
+target_link_libraries(tddft_test_lib Threads::Threads GTest::gtest_main GTest::gmock_main)
+#target_include_directories(tddft_test_lib PUBLIC $<$<COMPILE_LANGUAGE:CXX>:${GTEST_INCLUDE_DIRS}>)
 
 AddTest(
   TARGET tddft_middle_hamilt_test

source/module_hsolver/my_elpa.h

@@ -7,6 +7,11 @@
 #include <elpa/elpa_version.h>
 #include <limits.h>
 
+#if ELPA_API_VERSION < 20221101
+extern "C"
+{
+#endif
+
 struct elpa_struct;
 typedef struct elpa_struct *elpa_t;
 
@@ -19,15 +24,23 @@ typedef struct elpa_autotune_struct *elpa_autotune_t;
 // between C99 (e.g. double complex) and C++11 (std::complex).
 // Thus, we have to define a wrapper of complex over the c api
 // for compatiability.
+#if ELPA_API_VERSION < 20221101
 #define complex _Complex
+#endif
 #include <elpa/elpa_generated.h>
+#if ELPA_API_VERSION < 20221101
 #undef complex
+#endif
 #include <elpa/elpa_generic.h>
 
 #define ELPA_2STAGE_REAL_GPU    ELPA_2STAGE_REAL_NVIDIA_GPU
 #define ELPA_2STAGE_COMPLEX_GPU ELPA_2STAGE_COMPLEX_NVIDIA_GPU
 
 const char *elpa_strerr(int elpa_error);
 
+#if ELPA_API_VERSION < 20221101
+}//extern "C"
 #endif
-#endif
+
+#endif //__ELPA
+#endif //ELPA_H

source/module_hsolver/test/diago_elpa_utils.h

@@ -13,10 +13,7 @@
 #include <vector>
 
 #ifdef __ELPA
-extern "C"
-{
 #include "module_hsolver/my_elpa.h"
-}
 #endif
 
 namespace LCAO_DIAGO_TEST