[libc] Fix argument types for {f,}truncate specs

The current argument types are currently switched around for ftruncate
and truncate. Currently passes tests because the internal definitions
inside the __llvm_libc namespace are fine.

Reviewed By: michaelrj, thesamesam, sivachandra

Differential Revision: https://reviews.llvm.org/D152664

libc/spec/posix.td

@@ -425,7 +425,7 @@ def POSIX : StandardSpec<"POSIX"> {
         FunctionSpec<
           "ftruncate",
           RetValSpec<IntType>,
-          [ArgSpec<ConstCharPtr>, ArgSpec<OffTType>]
+          [ArgSpec<IntType>, ArgSpec<OffTType>]
         >,
         FunctionSpec<
           "geteuid",
@@ -580,7 +580,7 @@ def POSIX : StandardSpec<"POSIX"> {
         FunctionSpec<
           "truncate",
           RetValSpec<IntType>,
-          [ArgSpec<IntType>, ArgSpec<OffTType>]
+          [ArgSpec<ConstCharPtr>, ArgSpec<OffTType>]
         >,
         FunctionSpec<
           "unlink",