Revert "Added version from config.inc to cmake project"

This reverts commit b469c26.

CBMC_VERSION is already being set (using the very same code) in the
top-level `CMakeLists.txt` file.

Author: tautschnig

src/CMakeLists.txt

@@ -1,12 +1,4 @@
-file(STRINGS
-        "${CMAKE_CURRENT_SOURCE_DIR}/config.inc"
-        cbmc_version_string
-        REGEX "CBMC_VERSION.*")
-
-string(REGEX REPLACE "CBMC_VERSION = (.*)" "\\1" CBMC_VERSION "${cbmc_version_string}")
-unset(cbmc_version_string)
-
-project(CBMC VERSION ${CBMC_VERSION})
+project(CBMC)
 
 find_package(BISON REQUIRED)
 find_package(FLEX REQUIRED)