CONFIG: support wmake -debug-O0, -debug-O1 etc.

- rearranged order of flags so that FOAM_EXTRA_CXXFLAGS is added
  after the WARN/OPT/DBUG flags

CONFIG: drop wmake rules for PGI compiler (defunct)

wmake/rules/General/Icc/c

@@ -5,6 +5,6 @@ cc          = icc$(COMPILER_VERSION)
 cARCH       =
 cDBUG       =
 cOPT        = -O2
-cWARN       = $(FOAM_EXTRA_CFLAGS)
+cWARN       =
 
 #------------------------------------------------------------------------------

wmake/rules/General/Icc/c++

@@ -10,16 +10,13 @@ c++DBUG     =
 c++OPT      = -O2
 ptFLAGS     = -DNoRepository
 
-# - Standard warnings
-# - Less restrictive warnings (may be needed for flex++, CGAL, etc.).
-
 c++WARN     = \
     -Wall -Wextra \
     -Wnon-virtual-dtor -Wno-unused-parameter -Wno-invalid-offsetof \
     -Wno-unknown-pragmas \
-    -diag-disable 327,654,1125,1292,2289,2304,11062,11074,11076 \
-    $(FOAM_EXTRA_CXXFLAGS)
+    -diag-disable 327,654,1125,1292,2289,2304,11062,11074,11076
 
+# Less restrictive warnings (eg, for flex++, CGAL, etc.)
 c++LESSWARN = \
     -diag-disable 1224,2026,2305