[CMake] Fix the static bindings workflow.

Rename LLDB_ALLOW_STATIC_BINDINGS to LLDB_USE_STATIC_BINDINGS and make
LLDB use the static bindings unconditionally when it's set. The current
variable is opaque because it *allows* LLDB to use the static bindings,
but only if SWIG is not found. If an incompatible version of swig is
found, it reports a fatal error. This serves no purpose other than to
confuse the user.

This patch simplifies things and makes the variable do what you expect.
When enabled, LLDB uses the static bindings. When disabled, we try to
generate them with SWIG.

Author: JDevlieghere

lldb/cmake/caches/Apple-lldb-Linux.cmake

@@ -1,9 +1,5 @@
 include(${CMAKE_CURRENT_LIST_DIR}/Apple-lldb-base.cmake)
 
-# Begin Swift Mods
-set(LLDB_ALLOW_STATIC_BINDINGS ON CACHE BOOL "")
-# End Swift Mods
-
 set(LLVM_DISTRIBUTION_COMPONENTS
   lldb
   liblldb

lldb/cmake/caches/Apple-lldb-base.cmake

@@ -7,3 +7,7 @@ set(LLVM_ENABLE_MODULES OFF CACHE BOOL "")
 
 set(LIBCXX_ENABLE_SHARED OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_STATIC OFF CACHE BOOL "")
+
+# Begin Swift Mods
+set(LLDB_USE_STATIC_BINDINGS ON CACHE BOOL "")
+# End Swift Mods

lldb/cmake/modules/LLDBConfig.cmake

@@ -54,7 +54,7 @@ option(LLDB_USE_SYSTEM_DEBUGSERVER "Use the system's debugserver for testing (Da
 
 # BEGIN SWIFT MOD
 option(LLDB_ENABLE_SWIFT_SUPPORT "Enable swift support" ON)
-option(LLDB_ALLOW_STATIC_BINDINGS "Enable using static/baked language bindings if swig is not present." OFF)
+option(LLDB_USE_STATIC_BINDINGS "Use the static Python bindings." OFF)
 # END SWIFT CODE
 
 if(LLDB_BUILD_FRAMEWORK)

lldb/scripts/CMakeLists.txt

@@ -13,19 +13,21 @@ if(LLDB_BUILD_FRAMEWORK)
   set(framework_arg --framework --target-platform Darwin)
 endif()
 
-find_package(SWIG)
-if(${SWIG_FOUND})
-  set(SWIG_MIN_VERSION "2.0.0")
-  if (${SWIG_VERSION} VERSION_LESS ${SWIG_MIN_VERSION})
-    message(FATAL_ERROR "LLDB requires swig ${SWIG_MIN_VERSION}, your version is ${SWIG_VERSION}.")
-  endif()
-  set(PREPARE_BINDINGS_ARGS
-    "--swig-executable=${SWIG_EXECUTABLE}")
-elseif(${LLDB_ALLOW_STATIC_BINDINGS})
+if(${LLDB_USE_STATIC_BINDINGS})
   set(PREPARE_BINDINGS_ARGS
     --use-static-binding)
 else()
-  message(FATAL_ERROR "swig not found and static bindings not permitted - install swig or specify -DLLDB_ALLOW_STATIC_BINDINGS=1")
+  find_package(SWIG)
+  if(${SWIG_FOUND})
+    set(SWIG_MIN_VERSION "2.0.0")
+    if (${SWIG_VERSION} VERSION_LESS ${SWIG_MIN_VERSION})
+      message(FATAL_ERROR "LLDB requires swig ${SWIG_MIN_VERSION}, your version is ${SWIG_VERSION}.")
+    endif()
+    set(PREPARE_BINDINGS_ARGS
+      "--swig-executable=${SWIG_EXECUTABLE}")
+  else()
+    message(FATAL_ERROR "LLDB requires swig ${SWIG_MIN_VERSION}. To use the static bindings instead use -DLLDB_USE_STATIC_BINDINGS=ON")
+  endif()
 endif()
 
 add_custom_command(