Codemodelbackend: Check properly for LLVM_INSTALL_DIR

* Check also the environment variable
* Check before including clang_installation.pri
* Move the check to src/tools.pro to be consistent with the rest

Change-Id: I0ffc43b5cc8df49fdc6141d356e34de22041eabb
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/tools/codemodelbackend/codemodelbackend.pri

@@ -11,8 +11,6 @@ include(ipcsource/codemodelbackendclangipc-source.pri)
 include(../../../qtcreator.pri)
 include(../../shared/clang/clang_installation.pri)
 
-requires(!isEmpty(LLVM_INSTALL_DIR))
-
 LIBS += -L$$OUT_PWD/../codemodelbackendipc/lib/qtcreator -lCodemodelbackendipc -lSqlite
 LIBS += $$LLVM_LIBS
 INCLUDEPATH += $$LLVM_INCLUDEPATH

src/tools/tools.pro

@@ -6,8 +6,7 @@ SUBDIRS = qtpromaker \
      valgrindfake \
      3rdparty \
      qml2puppet \
-     buildoutputparser \
-     codemodelbackend
+     buildoutputparser
 
 win32 {
     SUBDIRS += qtcdebugger \
@@ -19,6 +18,11 @@ mac {
     SUBDIRS += iostool
 }
 
+isEmpty(LLVM_INSTALL_DIR):LLVM_INSTALL_DIR=$$(LLVM_INSTALL_DIR)
+!isEmpty(LLVM_INSTALL_DIR) {
+    SUBDIRS += codemodelbackend
+}
+
 BUILD_CPLUSPLUS_TOOLS = $$(BUILD_CPLUSPLUS_TOOLS)
 !isEmpty(BUILD_CPLUSPLUS_TOOLS) {
     SUBDIRS += cplusplus-ast2png \