Try to find the brew preifx to find the installed packages correctly

Author: florianbecker

cmake/find_package.cmake

@@ -37,10 +37,23 @@ endif()
 find_package(Threads REQUIRED)
 unset(CMAKE_REQUIRED_FLAGS)
 
+#find_program(BREW_PROGRAM "brew")
+#set(HOMEBREW_PREFIX "brew --prefix")
+
+if (NOT DEFINED ${HOMEBREW_PREFIX})
+  if (DEFINED ENV{HOMEBREW_PREFIX} AND IS_DIRECTORY ENV{HOMEBREW_PREFIX})
+    set(HOMEBREW_PREFIX ENV{HOMEBREW_PREFIX})
+  elseif(IS_DIRECTORY /opt/homebrew)
+    set(HOMEBREW_PREFIX /opt/homebrew)
+  else()
+    set(HOMEBREW_PREFIX /usr/local)
+  endif()
+endif()
+
 if(UNIX AND NOT APPLE)
   set(ICU_ROOT /usr/lib/x86_64-linux-gnu/)
 elseif(APPLE)
-  set(ICU_ROOT /usr/local/opt/icu4c/)
+  set(ICU_ROOT ${HOMEBREW_PREFIX}/opt/icu4c/)
 endif()
 find_package(ICU 66 COMPONENTS i18n uc)