Fix STM32F10x CMSIS ASM for newer compilers (#137)

Co-authored-by: Steve Karg <skarg@users.sourceforge.net>

ports/stm32f10x/CMSIS/core_cm3.c

@@ -1,4 +1,4 @@
-/**************************************************************************/ /**
+/**
  * @file     core_cm3.c
  * @brief    CMSIS Cortex-M3 Core Peripheral Access Layer Source File
  * @version  V1.30
@@ -19,8 +19,7 @@
  * ARM SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR
  * CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
  *
-                                                                              ******************************************************************************/
-
+ */
 #include <stdint.h>
 
 /* define compiler specific symbols */
@@ -689,7 +688,7 @@ uint32_t __STREXB(uint8_t value, uint8_t *addr)
     uint32_t result = 0;
 
     __ASM volatile("strexb %0, %2, [%1]"
-                   : "=r"(result)
+                   : "=&r"(result)
                    : "r"(addr), "r"(value));
     return (result);
 }
@@ -708,7 +707,7 @@ uint32_t __STREXH(uint16_t value, uint16_t *addr)
     uint32_t result = 0;
 
     __ASM volatile("strexh %0, %2, [%1]"
-                   : "=r"(result)
+                   : "=&r"(result)
                    : "r"(addr), "r"(value));
     return (result);
 }