Recognize SCO UnixWare C/C++ compilers (#11700)

These compilers define __SCO_VERSION__ as VvvYYYYMML:

     V = major version
    vv = minor version
  YYYY = release year
    MM = release month

http://osr600doc.sco.com/en/manCP/cc.CP.html
http://osr600doc.sco.com/en/manCP/CC.CP.html

Modules/CMakeCCompilerId.c.in

@@ -48,6 +48,9 @@
 #elif defined(__TI_COMPILER_VERSION__)
 # define COMPILER_ID "TI_DSP"
 
+#elif defined(__SCO_VERSION__)
+# define COMPILER_ID "SCO"
+
 #elif defined(__GNUC__)
 # define COMPILER_ID "GNU"
 

Modules/CMakeCXXCompilerId.cpp.in

@@ -50,6 +50,9 @@
 #elif defined(__TI_COMPILER_VERSION__)
 # define COMPILER_ID "TI_DSP"
 
+#elif defined(__SCO_VERSION__)
+# define COMPILER_ID "SCO"
+
 #elif defined(__GNUC__)
 # define COMPILER_ID "GNU"