[CMake] Fix dependencies for generating install_tactic.cpp.

Previously CMake was not aware of which headers files the generation
of `install_tactic.cpp` depended on. Consequently this could result
in broken incremental builds if

* Existing headers that declared tactics/probes changed.
* New tactics/probes were added to new header files.

Now the `z3_add_component()` CMake function has been modifed to take an
optional `TACTIC_HEADERS` argument which allows the headers that declare
tactics/probes to be explicitly listed. The necessary component
declarations have been modified to declare their tactic/probe header
files.

With this information CMake will now regenerate `install_tactic.cpp`
correctly.

This required the `mk_install_tactic_cpp_internal()` function to be
changed to take a list of header files rather than a list of component
source directories. The two consumers (CMake and Python/Makefile build
systems) of this function have been modified to work with this change.

This partially fixes #1030.

src/qe/CMakeLists.txt

@@ -23,6 +23,13 @@ z3_add_component(qe
     nlsat_tactic
     nlsat
     sat
-    smt   
-    tactic 
+    smt
+    tactic
+  TACTIC_HEADERS
+    nlqsat.h
+    qe_lite.h
+    qe_sat_tactic.h
+    qe_tactic.h
+    qsat.h
+    vsubst_tactic.h
 )