Add AsciiPrint and AsciiVSPrint

Per https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Library/PrintLib.h
AsciiPrint() is the official name of APrint() so declare it as such and define
an APrint alias for compatibility.

Also add an AsciiVSPrint() to print a formatted ASCII string to a buffer using
a va_list. AsciiPrint() too is defined in EDK2's PrintLib.h, though our implementation
just invokes the Unicode version and then converts the buffer to ASCII.

inc/efilib.h

@@ -580,11 +580,22 @@ IPrintAt (
     );
 
 UINTN
-APrint (
+AsciiPrint (
     IN CONST CHAR8    *fmt,
     ...
     );
 
+/* For compatibility with previous versions */
+#define APrint AsciiPrint
+
+UINTN
+AsciiVSPrint(
+    OUT CHAR8         *Str,
+    IN  UINTN         StrSize,
+    IN  CONST CHAR8   *fmt,
+    va_list           args
+);
+
 VOID
 ValueToHex (
     IN CHAR16   *Buffer,

lib/print.c

@@ -405,7 +405,7 @@ _PoolCatPrint (
     IN OUT POOL_PRINT   *spc,
     IN INTN             (EFIAPI *Output)(VOID *context, CHAR16 *str)
     )
-// Dispath function for SPrint, PoolPrint, and CatPrint
+// Dispatch function for SPrint, PoolPrint, and CatPrint
 {
     PRINT_STATE         ps;
 
@@ -810,7 +810,7 @@ _IPrint (
 
 
 UINTN
-APrint (
+AsciiPrint (
     IN CONST CHAR8    *fmt,
     ...
     )
@@ -842,6 +842,64 @@ Returns:
 }
 
 
+UINTN
+AsciiVSPrint (
+    OUT CHAR8         *Str,
+    IN UINTN          StrSize,
+    IN CONST CHAR8    *fmt,
+    va_list           args
+)
+/*++
+
+Routine Description:
+
+    Prints a formatted ascii string to a buffer using a va_list
+
+Arguments:
+
+    Str         - Output buffer to print the formatted string into
+
+    StrSize     - Size of Str.  String is truncated to this size.
+                  A size of 0 means there is no limit
+
+    fmt         - The format string
+
+    args        - va_list
+
+
+Returns:
+
+    String length returned in buffer
+
+--*/
+// Use Unicode VSPrint() and convert back to ASCII
+{
+    CHAR16 *UnicodeStr, *UnicodeFmt;
+    UINTN i, Len;
+
+    UnicodeStr = AllocatePool(StrSize * sizeof(CHAR16));
+    if (!UnicodeStr)
+        return 0;
+
+    UnicodeFmt = PoolPrint(L"%a", fmt);
+    if (!UnicodeFmt) {
+        FreePool(UnicodeStr);
+        return 0;
+    }
+
+    Len = VSPrint(UnicodeStr, StrSize, UnicodeFmt, args);
+    FreePool(UnicodeFmt);
+
+    // The strings are ASCII so just do a plain Unicode conversion
+    for (i = 0; i < Len; i++)
+        Str[i] = (CHAR8)UnicodeStr[i];
+    Str[Len] = 0;
+    FreePool(UnicodeStr);
+
+    return Len;
+}
+
+
 STATIC
 VOID
 PFLUSH (