Do not use non-ASCII chars in sources

No encodings are guaranteed in C compilers, and other than UTF-8
encodings may be assumed in some platforms, e.g., CP932 on Windows
Japanese edition, and may result in compilation errors.

coroutine/ppc/Context.S

@@ -3,7 +3,7 @@
 ; Some relevant examples: https://github.com/gcc-mirror/gcc/blob/master/libphobos/libdruntime/config/powerpc/switchcontext.S
 ; https://github.com/gcc-mirror/gcc/blob/master/libgcc/config/rs6000/darwin-gpsave.S
 ; https://www.ibm.com/docs/en/aix/7.2?topic=epilogs-saving-gprs-only
-; ppc32 version may be re-written compactly with stmw/lwm, but the code wonʼt be faster, see: https://github.com/ruby/ruby/pull/5927#issuecomment-1139730541
+; ppc32 version may be re-written compactly with stmw/lwm, but the code won't be faster, see: https://github.com/ruby/ruby/pull/5927#issuecomment-1139730541
 
 ; Notice that this code is only for Darwin (macOS). Darwin ABI differs from AIX and ELF.
 ; To add support for AIX, *BSD or *Linux, please make separate implementations.

coroutine/ppc/Context.h

@@ -13,7 +13,7 @@
 
 enum {
   COROUTINE_REGISTERS =
-  20  /* 19 general purpose registers (r13–r31) and 1 return address */
+  20  /* 19 general purpose registers (r13-r31) and 1 return address */
   + 4  /* space for fiber_entry() to store the link register */
 };
 

coroutine/ppc64/Context.h

@@ -12,7 +12,7 @@
 
 enum {
   COROUTINE_REGISTERS =
-  20  /* 19 general purpose registers (r13–r31) and 1 return address */
+  20  /* 19 general purpose registers (r13-r31) and 1 return address */
   + 4  /* space for fiber_entry() to store the link register */
 };