[libc++] Use inline instead of static in headers.

This has been tested as part of D156609.

Author: mordante

libcxx/src/std_stream.h

@@ -113,15 +113,15 @@ __stdinbuf<_CharT>::uflow()
     return __getchar(true);
 }
 
-static bool __do_getc(FILE *__fp, char *__pbuf) {
+inline bool __do_getc(FILE *__fp, char *__pbuf) {
     int __c = getc(__fp);
     if (__c == EOF)
         return false;
     *__pbuf = static_cast<char>(__c);
     return true;
 }
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-static bool __do_getc(FILE *__fp, wchar_t *__pbuf) {
+inline bool __do_getc(FILE *__fp, wchar_t *__pbuf) {
     wint_t __c = getwc(__fp);
     if (__c == WEOF)
         return false;
@@ -130,13 +130,13 @@ static bool __do_getc(FILE *__fp, wchar_t *__pbuf) {
 }
 #endif
 
-static bool __do_ungetc(int __c, FILE *__fp, char __dummy) {
+inline bool __do_ungetc(int __c, FILE *__fp, char __dummy) {
     if (ungetc(__c, __fp) == EOF)
         return false;
     return true;
 }
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-static bool __do_ungetc(std::wint_t __c, FILE *__fp, wchar_t __dummy) {
+inline bool __do_ungetc(std::wint_t __c, FILE *__fp, wchar_t __dummy) {
     if (ungetwc(__c, __fp) == WEOF)
         return false;
     return true;
@@ -324,13 +324,13 @@ __stdoutbuf<_CharT>::__stdoutbuf(FILE* __fp, state_type* __st)
         __always_noconv_ = true;
 }
 
-static bool __do_fputc(char __c, FILE* __fp) {
+inline bool __do_fputc(char __c, FILE* __fp) {
     if (fwrite(&__c, sizeof(__c), 1, __fp) != 1)
         return false;
     return true;
 }
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-static bool __do_fputc(wchar_t __c, FILE* __fp) {
+inline bool __do_fputc(wchar_t __c, FILE* __fp) {
     // fputwc works regardless of wide/narrow mode of stdout, while
     // fwrite of wchar_t only works if the stream actually has been set
     // into wide mode.