cmake, test: Introduce SECP256K1_TESTNAME_PREFIX variable

This change enables downstream projects to add a custom prefix to the
libsecp256k1 tests, facilitating the use of `ctest` regex matching
options.

examples/CMakeLists.txt

@@ -9,7 +9,7 @@ function(add_example name)
     $<$<PLATFORM_ID:Windows>:bcrypt>
   )
   set(test_name ${name}_example)
-  add_test(NAME ${test_name} COMMAND ${target_name})
+  add_test(NAME ${SECP256K1_TESTNAME_PREFIX}${test_name} COMMAND ${target_name})
   if(BUILD_SHARED_LIBS AND MSVC)
     # The DLL must reside either in the same folder where the executable is
     # or somewhere in PATH. Using the latter option.

src/CMakeLists.txt

@@ -87,12 +87,12 @@ endif()
 if(SECP256K1_BUILD_TESTS)
   add_executable(noverify_tests tests.c)
   target_link_libraries(noverify_tests secp256k1_precomputed secp256k1_asm)
-  add_test(NAME noverify_tests COMMAND noverify_tests)
+  add_test(NAME ${SECP256K1_TESTNAME_PREFIX}noverify_tests COMMAND noverify_tests)
   if(NOT CMAKE_BUILD_TYPE STREQUAL "Coverage")
     add_executable(tests tests.c)
     target_compile_definitions(tests PRIVATE VERIFY)
     target_link_libraries(tests secp256k1_precomputed secp256k1_asm)
-    add_test(NAME tests COMMAND tests)
+    add_test(NAME ${SECP256K1_TESTNAME_PREFIX}tests COMMAND tests)
   endif()
 endif()
 
@@ -101,7 +101,7 @@ if(SECP256K1_BUILD_EXHAUSTIVE_TESTS)
   add_executable(exhaustive_tests tests_exhaustive.c)
   target_link_libraries(exhaustive_tests secp256k1_asm)
   target_compile_definitions(exhaustive_tests PRIVATE $<$<NOT:$<CONFIG:Coverage>>:VERIFY>)
-  add_test(NAME exhaustive_tests COMMAND exhaustive_tests)
+  add_test(NAME ${SECP256K1_TESTNAME_PREFIX}exhaustive_tests COMMAND exhaustive_tests)
 endif()
 
 if(SECP256K1_BUILD_CTIME_TESTS)