Escape special characters before using source/build dirs in regex

If "^${CMAKE_SOURCE_DIR}" contains special characters, the regular
expression will break with an error like this for Garfield++:

RegularExpression::compile(): Nested *?+.
RegularExpression::compile(): Error in compile.
CMake Error at .../RootNewMacros.cmake:288 (if):
  if given arguments:

    "NOT" "IS_ABSOLUTE" "incdir"
    "OR" "incdir" "MATCHES" "^/<...>/src/Garfield++/HEAD"
    "OR" "incdir" "MATCHES" "^"
    "OR" "incdir" "MATCHES" "^"

  Regular expression
  "^/<...>/src/Garfield++/HEAD"
  cannot compile
Call Stack (most recent call first):
  CMakeLists.txt:118 (ROOT_GENERATE_DICTIONARY)

Also, the (current) build directory is CMAKE_(CURRENT_)BINARY_DIR.
Related Jira issue: ROOT-10210.

Author: amadio

cmake/modules/RootNewMacros.cmake

@@ -290,11 +290,14 @@ function(ROOT_GENERATE_DICTIONARY dictionary)
       else()
         set(incdirs_in_build)
         set(incdirs_in_prefix)
+        string(REGEX REPLACE "([][+.*()^])" "\\\\\\1" _source_dir "${CMAKE_SOURCE_DIR}")
+        string(REGEX REPLACE "([][+.*()^])" "\\\\\\1" _binary_dir "${CMAKE_BINARY_DIR}")
+        string(REGEX REPLACE "([][+.*()^])" "\\\\\\1" _curr_binary_dir "${CMAKE_CURRENT_BINARY_DIR}")
         foreach(incdir ${incdirs})
-          if(NOT IS_ABSOLUTE incdir
-             OR incdir MATCHES "^${CMAKE_SOURCE_DIR}"
-             OR incdir MATCHES "^${CMAKE_CURRENT_BUILD_DIR}"
-             OR incdir MATCHES "^${CMAKE_BUILD_DIR}")
+          if(NOT IS_ABSOLUTE ${incdir}
+             OR ${incdir} MATCHES "^${_source_dir}"
+             OR ${incdir} MATCHES "^${_binary_dir}"
+             OR ${incdir} MATCHES "^${_curr_binary_dir}")
             list(APPEND incdirs_in_build
                  ${incdir})
           else()