toolchain: Remove powerpc64 libc restriction

Starting with version 1.1.15, musl supports powerpc64.

There are no known users of powerpc64 yet.

This is effectively a revert of 0de93311e1

Signed-off-by: Rosen Penev <rosenp@gmail.com>

toolchain/Config.in

@@ -238,7 +238,6 @@ comment "C Library"
 choice
 	prompt "C Library implementation" if TOOLCHAINOPTS
 	default LIBC_USE_UCLIBC if arc
-	default LIBC_USE_GLIBC if powerpc64
 	default LIBC_USE_MUSL
 	help
 	  Select the C library implementation.
@@ -257,7 +256,7 @@ choice
 	config LIBC_USE_MUSL
 		select USE_MUSL
 		bool "Use musl"
-		depends on !(arc || powerpc64)
+		depends on !arc
 
 endchoice
 
@@ -275,7 +274,6 @@ config GDB
 	  Enable if you want to build the gdb.
 
 config USE_GLIBC
-	default y if !TOOLCHAINOPTS && !EXTERNAL_TOOLCHAIN && !NATIVE_TOOLCHAIN && (powerpc64)
 	bool
 
 config USE_UCLIBC
@@ -283,7 +281,7 @@ config USE_UCLIBC
 	bool
 
 config USE_MUSL
-	default y if !TOOLCHAINOPTS && !EXTERNAL_TOOLCHAIN && !NATIVE_TOOLCHAIN && !(arc || powerpc64)
+	default y if !TOOLCHAINOPTS && !EXTERNAL_TOOLCHAIN && !NATIVE_TOOLCHAIN && !(arc)
 	bool
 
 config SSP_SUPPORT