Bug 1657609 - commonize PARAM_BUFFER_COUNT for PPC Linux; r=mccr8

There's no reason to have a different count depending on whether we have
floating-point registers or not; xpidl functions will have the same number
of parameters regardless.  This change also synchronizes soft-float PPC with
every other architecture.

Differential Revision: https://phabricator.services.mozilla.com/D86210

xpcom/reflect/xptcall/md/unix/xptcstubs_ppc_linux.cpp

@@ -14,13 +14,12 @@
 // area. The stack pointer has to retain 16-byte alignment, longlongs
 // and doubles are aligned on 8-byte boundaries.
 #ifndef __NO_FPRS__
-#define PARAM_BUFFER_COUNT     16
 #define GPR_COUNT               8
 #define FPR_COUNT               8
 #else
-#define PARAM_BUFFER_COUNT      8
 #define GPR_COUNT               8
 #endif
+#define PARAM_BUFFER_COUNT     16
 // PrepareAndDispatch() is called by SharedStub() and calls the actual method.
 //
 // - 'args[]' contains the arguments passed on stack