DEV-17460 updated the cmake SERVER variable init to work reliably

indra/CMakeLists.txt

@@ -70,7 +70,16 @@ if (VIEWER)
   add_dependencies(viewer secondlife-bin)
 endif (VIEWER)
 
-add_custom_target(server)
+# Linux builds the viewer and server in 2 separate projects
+# In order for ./develop.py build server to work on linux, 
+# the viewer project needs a server target.
+# This is not true for mac and windows.
+if (LINUX) 
+  add_custom_target(server)
+endif (LINUX)
 if (SERVER)
+  if (NOT LINUX)
+    add_custom_target(server)
+  endif (NOT LINUX)
   include(${SERVER_PREFIX}Server.cmake)
 endif (SERVER)

indra/cmake/Variables.cmake

@@ -81,9 +81,9 @@ set(VIEWER ON CACHE BOOL "Build Second Life viewer.")
 
 set(STANDALONE OFF CACHE BOOL "Do not use Linden-supplied prebuilt libraries.")
 
-if (NOT STANDALONE AND EXISTS ${LIBS_PREBUILT_DIR}/include/havok)
+if (NOT STANDALONE AND EXISTS ${CMAKE_SOURCE_DIR}/llphysics)
     set(SERVER ON CACHE BOOL "Build Second Life server software.")
-endif (NOT STANDALONE AND EXISTS ${LIBS_PREBUILT_DIR}/include/havok)
+endif (NOT STANDALONE AND EXISTS ${CMAKE_SOURCE_DIR}/llphysics)
 
 if (LINUX AND SERVER AND VIEWER)
   MESSAGE(FATAL_ERROR "