changed target allarch into allzstd

allzstd contains only zstd-related tests.
allmost = allzstd + zwrapper tests (which require zlib)
diff --git a/appveyor.yml b/appveyor.yml
index 1815563..91f1179 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -9,19 +9,19 @@
     - COMPILER: "gcc"
       HOST:     "mingw"
       PLATFORM: "x64"
-      SCRIPT:   "make allarch && make -C tests test-symbols fullbench-dll fullbench-lib"
+      SCRIPT:   "make allzstd && make -C tests test-symbols fullbench-dll fullbench-lib"
       ARTIFACT: "true"
       BUILD:    "true"
     - COMPILER: "gcc"
       HOST:     "mingw"
       PLATFORM: "x86"
-      SCRIPT:   "make allarch"
+      SCRIPT:   "make allzstd"
       ARTIFACT: "true"
       BUILD:    "true"
     - COMPILER: "clang"
       HOST:     "mingw"
       PLATFORM: "x64"
-      SCRIPT:   "MOREFLAGS='--target=x86_64-w64-mingw32 -Werror -Wconversion -Wno-sign-conversion' make allarch"
+      SCRIPT:   "MOREFLAGS='--target=x86_64-w64-mingw32 -Werror -Wconversion -Wno-sign-conversion' make allzstd"
       BUILD:    "true"
 
     - COMPILER: "gcc"
@@ -172,15 +172,15 @@
     - COMPILER: "gcc"
       HOST:     "mingw"
       PLATFORM: "x64"
-      SCRIPT:   "make allarch"
+      SCRIPT:   "make allzstd"
     - COMPILER: "gcc"
       HOST:     "mingw"
       PLATFORM: "x86"
-      SCRIPT:   "make allarch"
+      SCRIPT:   "make allzstd"
     - COMPILER: "clang"
       HOST:     "mingw"
       PLATFORM: "x64"
-      SCRIPT:   "MOREFLAGS='--target=x86_64-w64-mingw32 -Werror -Wconversion -Wno-sign-conversion' make allarch"
+      SCRIPT:   "MOREFLAGS='--target=x86_64-w64-mingw32 -Werror -Wconversion -Wno-sign-conversion' make allzstd"
 
     - COMPILER: "visual"
       HOST:     "visual"