Default linker to ld on linux and fix missing headers (#2402)

* default linker to ld on linux

* fix failing test following toolchain change

* add missing header following platform change

Author: cpichard

testsuite/test_0134/data/test.cpp

@@ -12,6 +12,7 @@
 
 #include <cinttypes>
 #include <vector>
+#include <string>
 
 PXR_NAMESPACE_USING_DIRECTIVE
 

testsuite/test_0142/data/test.cpp

@@ -3,6 +3,7 @@
 #include <cstdio>
 #include <cstring>
 #include <iostream>
+#include <string>
 
 int main(int argc, char **argv)
 {

testsuite/test_0146/data/test.cpp

@@ -8,6 +8,7 @@
 
 #include <cinttypes>
 #include <vector>
+#include <string>
 
 PXR_NAMESPACE_USING_DIRECTIVE
 

testsuite/test_0208/data/test.cpp

@@ -4,6 +4,7 @@
 #include <cstring>
 #include <iostream>
 #include <vector>
+#include <string>
 
 int main(int argc, char **argv)
 {

testsuite/test_2072.1/data/test.cpp

@@ -1,5 +1,5 @@
 #include <ai.h>
-
+#include <stdio.h>
 //#define LOG_FLAGS AI_LOG_ALL
 #define LOG_FLAGS AI_LOG_WARNINGS | AI_LOG_ERRORS
 

testsuite/test_2072.2/data/test.cpp

@@ -1,5 +1,5 @@
 #include <ai.h>
-
+#include <stdio.h>
 //#define LOG_FLAGS AI_LOG_ALL
 #define LOG_FLAGS AI_LOG_WARNINGS | AI_LOG_ERRORS
 

testsuite/test_2303/data/test.cpp

@@ -1,6 +1,7 @@
 #include <ai.h>
 
 #include <vector>
+#include <string>
 
 //#define LOG_FLAGS AI_LOG_ALL
 #define LOG_FLAGS AI_LOG_WARNINGS | AI_LOG_ERRORS

tools/scons-custom/site_tools/clang.py

@@ -152,7 +152,7 @@ class ClangWarning(SCons.Warnings.Warning): pass
    # Special linker detection in linux
    if sa.system.is_linux:
       # Name of the linker (eg. ld, gold, bfd, lld, etc.). It defaults to "gold"
-      linker_name = env.get('LINKER_NAME', 'gold').replace('ld.', '', 1)
+      linker_name = env.get('LINKER_NAME', 'ld').replace('ld.', '', 1)
       # Regular expresions for detecting the linker version
       regex_version = r'(?:[0-9]+)(?:\.(?:[0-9])+)*'
       linker_regex = {