Return -no-canonical-prefixes for riskv32/64 test

W/o -no-canonical-prefixes CC1: clang{{.*}} "-cc1" "-triple" "riscv32"
does not match clang output for some setups.

See da62a5c.

Author: metaflow

clang/test/Driver/riscv32-toolchain.c

@@ -1,6 +1,6 @@
 // A basic clang -cc1 command-line, and simple environment check.
 
-// RUN: %clang %s -### --target=riscv32 \
+// RUN: %clang %s -### -no-canonical-prefixes --target=riscv32 \
 // RUN:   --gcc-toolchain=%S/Inputs/basic_riscv32_tree 2>&1 \
 // RUN:   | FileCheck -check-prefix=CC1 %s
 // CC1: clang{{.*}} "-cc1" "-triple" "riscv32"

clang/test/Driver/riscv64-toolchain.c

@@ -1,6 +1,6 @@
 // A basic clang -cc1 command-line, and simple environment check.
 
-// RUN: %clang %s -### --target=riscv64 \
+// RUN: %clang %s -### -no-canonical-prefixes --target=riscv64 \
 // RUN:   --gcc-toolchain=%S/Inputs/basic_riscv64_tree 2>&1 \
 // RUN:   | FileCheck -check-prefix=CC1 %s
 // CC1: clang{{.*}} "-cc1" "-triple" "riscv64"