esp32: add libgcc ROM functions to linker script

They are copied from ESP-IDF. They are always available (burned in the
mask ROM) so best to use them.

targets/esp32.ld

@@ -97,8 +97,106 @@ _heap_end = ORIGIN(DRAM) + LENGTH(DRAM);
 
 _stack_size = 4K;
 
-/* From ESP-IDF, included here as long as picolibc doesn't compile.
+/* From ESP-IDF:
+ * components/esp_rom/esp32/ld/esp32.rom.newlib-funcs.ld
+ * This is the subset that is sometimes used by LLVM during codegen, and thus
+ * must always be present.
  */
-memcpy    = 0x4000c2c8;
+memcpy  = 0x4000c2c8;
-memset    = 0x4000c44c;
+memmove = 0x4000c3c0;
-__udivdi3 = 0x4000cff8;
+memset  = 0x4000c44c;
+
+/* From ESP-IDF:
+ * components/esp_rom/esp32/ld/esp32.rom.libgcc.ld
+ * These are called from LLVM during codegen. The original license is Apache
+ * 2.0, but I believe that a list of function names and addresses can't really
+ * be copyrighted.
+ */
+__absvdi2      = 0x4006387c;
+__absvsi2      = 0x40063868;
+__adddf3       = 0x40002590;
+__addsf3       = 0x400020e8;
+__addvdi3      = 0x40002cbc;
+__addvsi3      = 0x40002c98;
+__ashldi3      = 0x4000c818;
+__ashrdi3      = 0x4000c830;
+__bswapdi2     = 0x40064b08;
+__bswapsi2     = 0x40064ae0;
+__clrsbdi2     = 0x40064b7c;
+__clrsbsi2     = 0x40064b64;
+__clzdi2       = 0x4000ca50;
+__clzsi2       = 0x4000c7e8;
+__cmpdi2       = 0x40063820;
+__ctzdi2       = 0x4000ca64;
+__ctzsi2       = 0x4000c7f0;
+__divdc3       = 0x400645a4;
+__divdf3       = 0x40002954;
+__divdi3       = 0x4000ca84;
+__divsi3       = 0x4000c7b8;
+__eqdf2        = 0x400636a8;
+__eqsf2        = 0x40063374;
+__extendsfdf2  = 0x40002c34;
+__ffsdi2       = 0x4000ca2c;
+__ffssi2       = 0x4000c804;
+__fixdfdi      = 0x40002ac4;
+__fixdfsi      = 0x40002a78;
+__fixsfdi      = 0x4000244c;
+__fixsfsi      = 0x4000240c;
+__fixunsdfsi   = 0x40002b30;
+__fixunssfdi   = 0x40002504;
+__fixunssfsi   = 0x400024ac;
+__floatdidf    = 0x4000c988;
+__floatdisf    = 0x4000c8c0;
+__floatsidf    = 0x4000c944;
+__floatsisf    = 0x4000c870;
+__floatundidf  = 0x4000c978;
+__floatundisf  = 0x4000c8b0;
+__floatunsidf  = 0x4000c938;
+__floatunsisf  = 0x4000c864;
+__gcc_bcmp     = 0x40064a70;
+__gedf2        = 0x40063768;
+__gesf2        = 0x4006340c;
+__gtdf2        = 0x400636dc;
+__gtsf2        = 0x400633a0;
+__ledf2        = 0x40063704;
+__lesf2        = 0x400633c0;
+__lshrdi3      = 0x4000c84c;
+__ltdf2        = 0x40063790;
+__ltsf2        = 0x4006342c;
+__moddi3       = 0x4000cd4c;
+__modsi3       = 0x4000c7c0;
+__muldc3       = 0x40063c90;
+__muldf3       = 0x4006358c;
+__muldi3       = 0x4000c9fc;
+__mulsf3       = 0x400632c8;
+__mulsi3       = 0x4000c7b0;
+__mulvdi3      = 0x40002d78;
+__mulvsi3      = 0x40002d60;
+__nedf2        = 0x400636a8;
+__negdf2       = 0x400634a0;
+__negdi2       = 0x4000ca14;
+__negsf2       = 0x400020c0;
+__negvdi2      = 0x40002e98;
+__negvsi2      = 0x40002e78;
+__nesf2        = 0x40063374;
+__nsau_data    = 0x3ff96544;
+__paritysi2    = 0x40002f3c;
+__popcount_tab = 0x3ff96544;
+__popcountdi2  = 0x40002ef8;
+__popcountsi2  = 0x40002ed0;
+__powidf2      = 0x400638e4;
+__subdf3       = 0x400026e4;
+__subsf3       = 0x400021d0;
+__subvdi3      = 0x40002d20;
+__subvsi3      = 0x40002cf8;
+__truncdfsf2   = 0x40002b90;
+__ucmpdi2      = 0x40063840;
+__udiv_w_sdiv  = 0x40064bec;
+__udivdi3      = 0x4000cff8;
+__udivmoddi4   = 0x40064bf4;
+__udivsi3      = 0x4000c7c8;
+__umoddi3      = 0x4000d280;
+__umodsi3      = 0x4000c7d0;
+__umulsidi3    = 0x4000c7d8;
+__unorddf2     = 0x400637f4;
+__unordsf2     = 0x40063478;