[RISCV] Disable Atomics on all Non-A RISC-V targets

Author: lenary

src/librustc_target/spec/riscv32i_unknown_none_elf.rs

@@ -17,7 +17,7 @@ pub fn target() -> TargetResult {
         options: TargetOptions {
             linker: Some("rust-lld".to_string()),
             cpu: "generic-rv32".to_string(),
-            max_atomic_width: None,
+            max_atomic_width: Some(0),
             atomic_cas: false,
             features: String::new(),
             executables: true,

src/librustc_target/spec/riscv32imc_unknown_none_elf.rs

@@ -17,8 +17,7 @@ pub fn target() -> TargetResult {
         options: TargetOptions {
             linker: Some("rust-lld".to_string()),
             cpu: "generic-rv32".to_string(),
-            // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86005
-            max_atomic_width: None, //Some(32),
+            max_atomic_width: Some(0),
             atomic_cas: false,
             features: "+m,+c".to_string(),
             executables: true,