stop ./configure on Win32 if no library sources was specified,
the bug has been introduced in r2894

auto/lib/md5/conf

diff --git a/auto/lib/md5/conf b/auto/lib/md5/conf
index 246ee02..da1bf1b 100644
--- a/auto/lib/md5/conf
+++ b/auto/lib/md5/conf
@@ -94,8 +94,10 @@
             CORE_LIBS="$CORE_LIBS $ngx_feature_libs"
             MD5=YES
             MD5_LIB=$ngx_md5_lib
-        else
+        fi
+    fi
 
+    if [ $MD5 != YES ]; then
 cat << END
 
 $0: error: the HTTP cache module requires md5 functions
@@ -105,9 +107,7 @@
 --with-http_ssl_module --with-openssl=<path> options.
 
 END
-            exit 1
-        fi
-
+        exit 1
     fi
 
 fi

auto/lib/openssl/conf

diff --git a/auto/lib/openssl/conf b/auto/lib/openssl/conf
index 741e946..8218a5b 100644
--- a/auto/lib/openssl/conf
+++ b/auto/lib/openssl/conf
@@ -54,7 +54,10 @@
             have=NGX_SSL . auto/have
             CORE_LIBS="$CORE_LIBS $ngx_feature_libs $NGX_LIBDL"
             OPENSSL=YES
-        else
+        fi
+    fi
+
+    if [ $OPENSSL != YES ]; then
 
 cat << END
 
@@ -64,8 +67,7 @@
 with nginx by using --with-openssl=<path> option.
 
 END
-            exit 1
-        fi
+        exit 1
     fi
 
 fi

auto/lib/pcre/conf

diff --git a/auto/lib/pcre/conf b/auto/lib/pcre/conf
index 71c6fc5..3008f58 100644
--- a/auto/lib/pcre/conf
+++ b/auto/lib/pcre/conf
@@ -161,8 +161,10 @@
             CORE_INCS="$CORE_INCS $ngx_feature_path"
             CORE_LIBS="$CORE_LIBS $ngx_feature_libs"
             PCRE=YES
-        else
+        fi
+    fi
 
+    if [ $PCRE != YES ]; then
 cat << END
 
 $0: error: the HTTP rewrite module requires the PCRE library.
@@ -171,9 +173,7 @@
 statically from the source with nginx by using --with-pcre=<path> option.
 
 END
-            exit 1
-
-        fi
-
+        exit 1
     fi
+
 fi

auto/lib/zlib/conf

diff --git a/auto/lib/zlib/conf b/auto/lib/zlib/conf
index e44aa34..843dd5a 100644
--- a/auto/lib/zlib/conf
+++ b/auto/lib/zlib/conf
@@ -57,8 +57,10 @@
             CORE_LIBS="$CORE_LIBS $ngx_feature_libs"
             ZLIB=YES
             ngx_found=no
-        else
+        fi
+    fi
 
+    if [ $ZLIB != YES ]; then
 cat << END
 
 $0: error: the HTTP gzip module requires the zlib library.
@@ -67,8 +69,7 @@
 statically from the source with nginx by using --with-zlib=<path> option.
 
 END
-            exit 1
-        fi
+        exit 1
     fi
 
 fi

auto/summary

diff --git a/auto/summary b/auto/summary
index a7244a1..8a71cbe 100644
--- a/auto/summary
+++ b/auto/summary
@@ -38,7 +38,6 @@
     case $PCRE in
         YES)   echo "  + using system PCRE library" ;;
         NONE)  echo "  + PCRE library is not used" ;;
-        NO)    echo "  + PCRE library is not found" ;;
         *)     echo "  + using PCRE library: $PCRE" ;;
     esac
 fi
@@ -46,14 +45,12 @@
 case $OPENSSL in
     YES)   echo "  + using system OpenSSL library" ;;
     NONE)  echo "  + OpenSSL library is not used" ;;
-    NO)    echo "  + OpenSSL library is not found" ;;
     *)     echo "  + using OpenSSL library: $OPENSSL" ;;
 esac
 
 case $MD5 in
     YES)   echo "  + md5: using $MD5_LIB library" ;;
     NONE)  echo "  + md5 library is not used" ;;
-    NO)    echo "  + md5 library is not found" ;;
     *)     echo "  + using md5 library: $MD5" ;;
 esac
 
@@ -67,7 +64,6 @@
 case $ZLIB in
     YES)   echo "  + using system zlib library" ;;
     NONE)  echo "  + zlib library is not used" ;;
-    NO)    echo "  + zlib library is not found" ;;
     *)     echo "  + using zlib library: $ZLIB" ;;
 esac