x86, apic: untangle the send_IPI_*() jungle

Our send_IPI_*() methods and definitions are a twisted mess: the same
symbol is defined to different things depending on .config details,
in a non-transparent way.

 - spread out the quirks into separately named per apic driver methods

 - prefix the standard PC methods with default_

 - get rid of wrapper macro obfuscation

 - clean up various details

Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 10435a1..b62a381 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -347,7 +347,7 @@
  */
 void kgdb_roundup_cpus(unsigned long flags)
 {
-	send_IPI_allbutself(APIC_DM_NMI);
+	apic->send_IPI_allbutself(APIC_DM_NMI);
 }
 #endif