Add a facility to control tracing without recompiling

This will help greatly when it comes to diagnosing customer issues.
diff --git a/Makefile b/Makefile
index fe6368d..5c618d3 100644
--- a/Makefile
+++ b/Makefile
@@ -2262,6 +2262,7 @@
     src/core/channel/noop_filter.c \
     src/core/compression/algorithm.c \
     src/core/compression/message_compress.c \
+    src/core/debug/trace.c \
     src/core/httpcli/format_request.c \
     src/core/httpcli/httpcli.c \
     src/core/httpcli/httpcli_security_context.c \
@@ -2401,6 +2402,7 @@
 src/core/channel/noop_filter.c: $(OPENSSL_DEP)
 src/core/compression/algorithm.c: $(OPENSSL_DEP)
 src/core/compression/message_compress.c: $(OPENSSL_DEP)
+src/core/debug/trace.c: $(OPENSSL_DEP)
 src/core/httpcli/format_request.c: $(OPENSSL_DEP)
 src/core/httpcli/httpcli.c: $(OPENSSL_DEP)
 src/core/httpcli/httpcli_security_context.c: $(OPENSSL_DEP)
@@ -2557,6 +2559,7 @@
 $(OBJDIR)/$(CONFIG)/src/core/channel/noop_filter.o: 
 $(OBJDIR)/$(CONFIG)/src/core/compression/algorithm.o: 
 $(OBJDIR)/$(CONFIG)/src/core/compression/message_compress.o: 
+$(OBJDIR)/$(CONFIG)/src/core/debug/trace.o: 
 $(OBJDIR)/$(CONFIG)/src/core/httpcli/format_request.o: 
 $(OBJDIR)/$(CONFIG)/src/core/httpcli/httpcli.o: 
 $(OBJDIR)/$(CONFIG)/src/core/httpcli/httpcli_security_context.o: 
@@ -2734,6 +2737,7 @@
     src/core/channel/noop_filter.c \
     src/core/compression/algorithm.c \
     src/core/compression/message_compress.c \
+    src/core/debug/trace.c \
     src/core/httpcli/format_request.c \
     src/core/httpcli/httpcli.c \
     src/core/httpcli/httpcli_security_context.c \
@@ -2874,6 +2878,7 @@
 $(OBJDIR)/$(CONFIG)/src/core/channel/noop_filter.o: 
 $(OBJDIR)/$(CONFIG)/src/core/compression/algorithm.o: 
 $(OBJDIR)/$(CONFIG)/src/core/compression/message_compress.o: 
+$(OBJDIR)/$(CONFIG)/src/core/debug/trace.o: 
 $(OBJDIR)/$(CONFIG)/src/core/httpcli/format_request.o: 
 $(OBJDIR)/$(CONFIG)/src/core/httpcli/httpcli.o: 
 $(OBJDIR)/$(CONFIG)/src/core/httpcli/httpcli_security_context.o: