cabinet: Fix dead stores (llvm/clang).

dlls/cabinet/fci.c

diff --git a/dlls/cabinet/fci.c b/dlls/cabinet/fci.c
index ea745a6..ed413f8 100644
--- a/dlls/cabinet/fci.c
+++ b/dlls/cabinet/fci.c
@@ -462,7 +462,7 @@
     case 2:
       ul |= (((ULONG)(*pb++)) <<  8);
     case 1:
-      ul |= *pb++;
+      ul |= *pb;
     default:
       break;
   }

dlls/cabinet/fdi.c

diff --git a/dlls/cabinet/fdi.c b/dlls/cabinet/fdi.c
index 0825162..09d0fe7 100644
--- a/dlls/cabinet/fdi.c
+++ b/dlls/cabinet/fdi.c
@@ -2830,7 +2830,7 @@
 
       if (file->offset > CAB(offset)) {
         /* decode bytes and send them to /dev/null */
-        switch ((err = fdi_decomp(file, 0, decomp_state, pszCabPath, pfnfdin, pvUser))) {
+        switch (fdi_decomp(file, 0, decomp_state, pszCabPath, pfnfdin, pvUser)) {
           case DECR_OK:
             break;
           case DECR_USERABORT: