esp32: Adds functionality for application tracing over JTAG

- Implements application tracing module which allows to send arbitrary
   data to host over JTAG. This feature is useful for analyzing
   program modules behavior, dumping run-time application data etc.
 - Implements printf-like logging functions on top of apptrace module.
   This feature is a kind of semihosted printf functionality with lower
   overhead and impact on system behaviour as compared to standard printf.

components/esp32/ld/esp32.common.ld

@@ -86,6 +86,7 @@ SECTIONS
     *libesp32.a:panic.o(.literal .text .literal.* .text.*)
     *libesp32.a:core_dump.o(.literal .text .literal.* .text.*)
     *libesp32.a:heap_alloc_caps.o(.literal .text .literal.* .text.*)
+    *libesp32.a:app_trace.o(.literal .text .literal.* .text.*)
     *libphy.a:(.literal .text .literal.* .text.*)
     *librtc.a:(.literal .text .literal.* .text.*)
     *libsoc.a:(.literal .text .literal.* .text.*)
@@ -116,6 +117,7 @@ SECTIONS
     KEEP(*(.jcr))
     *(.dram1 .dram1.*)
     *libesp32.a:panic.o(.rodata .rodata.*)
+    *libesp32.a:app_trace.o(.rodata .rodata.*)
     _data_end = ABSOLUTE(.);
     . = ALIGN(4);
   } >dram0_0_seg