[flang] Add one missing "llvm_" prefix to gtest_main

[mgorny]

Summary

The target_link_libraries() call operates on gtest_main rather than
llvm_gtest_main. I think it was missed while prefixing all the tools
in 38151a08c21e0cdacd52af03e4bdff258f0bac6f.

[mgorny]

Disclaimer: I haven't tested it but the buildbot seems to be fast in catching problems.

[mgorny]

Gentle ping.

[awarzynski]

Thanks for spotting and for fixing this. Yes, looks like an obvious omission in https://reviews.llvm.org/rG38151a08c21e0cdacd52af03e4bdff258f0bac6f. Since this is for standalone builds, you want to keep an eye on flang-aarch64-out-of-tree. That's the only bot that builds this configuration taht I am aware of.

LGTM!

[mgorny]

Thanks!

flang/CMakeLists.txt

if(EXISTS ${UNITTEST_DIR}/googletest/include/gtest/gtest.h)
 
           PRIVATE
           "${UNITTEST_DIR}/googletest"
           "${UNITTEST_DIR}/googlemock"
           )
          find_package(Threads)
          target_link_libraries(llvm_gtest PUBLIC Threads::Threads)
         add_library(llvm_gtest_main ${UNITTEST_DIR}/UnitTestMain/TestMain.cpp)
-        target_link_libraries(gtest_main PUBLIC llvm_gtest)
+        target_link_libraries(llvm_gtest_main PUBLIC llvm_gtest)
       endif()
       set(FLANG_GTEST_AVAIL 1)
     else()
       message(WARNING
       "Unit-tests will be skipped as LLVM install does not include google-test related headers and libraries.")
       set(FLANG_GTEST_AVAIL 0)
     endif()
   endif()