gromacs: Let runtime logs show homebrew was used

Knowing that homebrew has patched the code and organized the build is
potentially valuable information for GROMACS users and developers
troubleshooting their runs.

Closes #85158.

Signed-off-by: Carlo Cabrera <30379873+carlocab@users.noreply.github.com>
Signed-off-by: BrewTestBot <1589480+BrewTestBot@users.noreply.github.com>

Formula/gromacs.rb

@@ -50,7 +50,8 @@ class Gromacs < Formula
     inreplace "src/gromacs/gromacs-config.cmake.cmakein", "@GROMACS_CXX_COMPILER@", cxx
 
     mkdir "build" do
-      system "cmake", "..", *std_cmake_args, "-DGROMACS_CXX_COMPILER=#{cxx}"
+      system "cmake", "..", *std_cmake_args, "-DGROMACS_CXX_COMPILER=#{cxx}",
+                                             "-DGMX_VERSION_STRING_OF_FORK=#{tap.user}"
       system "make", "install"
     end