Minor wording tweaks

Author: moxian

compiler/rustc_codegen_ssa/messages.ftl

@@ -52,8 +52,8 @@ codegen_ssa_expected_one_argument = expected one argument
 
 codegen_ssa_expected_used_symbol = expected `used`, `used(compiler)` or `used(linker)`
 
-codegen_ssa_export_name_llvm_intrinsic = exported symbol name must not start with "llvm."
-    .note = symbols starting with "llvm." are reserved for LLVM intrinsics and cannot be defined in user code
+codegen_ssa_export_name_llvm_intrinsic = exported symbol name must not start with `llvm.`
+    .note = symbols starting with `llvm.` are reserved for LLVM intrinsics
 
 codegen_ssa_extern_funcs_not_found = some `extern` functions couldn't be found; some native libraries may need to be installed or have their path specified
 

tests/ui/attributes/export_name-checks.rs

@@ -2,14 +2,14 @@
 
 // rdtsc is an existing LLVM intrinsic
 #[export_name = "llvm.x86.rdtsc"]
-//~^ ERROR: exported symbol name must not start with "llvm."
+//~^ ERROR: exported symbol name must not start with `llvm.`
 pub unsafe fn foo(a: u8) -> u8 {
     2 * a
 }
 
 // qwerty is not a real llvm intrinsic
 #[export_name = "llvm.x86.qwerty"]
-//~^ ERROR: exported symbol name must not start with "llvm."
+//~^ ERROR: exported symbol name must not start with `llvm.`
 pub unsafe fn bar(a: u8) -> u8 {
     2 * a
 }

tests/ui/attributes/export_name-checks.stderr

@@ -1,18 +1,18 @@
-error: exported symbol name must not start with "llvm."
+error: exported symbol name must not start with `llvm.`
   --> $DIR/export_name-checks.rs:4:17
    |
 LL | #[export_name = "llvm.x86.rdtsc"]
    |                 ^^^^^^^^^^^^^^^^
    |
-   = note: symbols starting with "llvm." are reserved for LLVM intrinsics and cannot be defined in user code
+   = note: symbols starting with `llvm.` are reserved for LLVM intrinsics
 
-error: exported symbol name must not start with "llvm."
+error: exported symbol name must not start with `llvm.`
   --> $DIR/export_name-checks.rs:11:17
    |
 LL | #[export_name = "llvm.x86.qwerty"]
    |                 ^^^^^^^^^^^^^^^^^
    |
-   = note: symbols starting with "llvm." are reserved for LLVM intrinsics and cannot be defined in user code
+   = note: symbols starting with `llvm.` are reserved for LLVM intrinsics
 
 error[E0648]: `export_name` may not contain null characters
   --> $DIR/export_name-checks.rs:17:15