Document dependency on a GNU awk extension

strtonum() is a GNU awk (gawk)-only extension. It is not portable, and other
implementations of awk may not support it.

Accordingly, document the dependency upon gawk specifically, and ensure snek
only calls gawk in it's Makefiles.

See further:
  - https://www.gnu.org/software/gawk/manual/html_node/Strtonum-Function.html
  - https://www.gnu.org/software/gawk/manual/html_node/String-Functions.html#index-strtonum_0028_0029-function-_0028gawk_0029

Signed-off-by: Rhys Kidd <rhyskidd@gmail.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

README.md

@@ -55,6 +55,7 @@ tools and other dependencies installed.
 To build Snek you need these dependencies:
 
   * [Lola](https://keithp.com/cgit/lola.git/)
+  * [gawk](https://www.gnu.org/software/gawk/)
   * [gcc-avr](https://ccrma.stanford.edu/~juanig/articles/wiriavrlib/AVR_GCC.html)
   * [avr-libc](https://www.nongnu.org/avr-libc/)
   * [gcc-arm-none-eabi](https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm/downloads)

ports/duemilanove/Makefile

@@ -84,7 +84,7 @@ $(HEX): $(ELF)
 
 $(ELF): $(SNEK_OBJ)
 	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
-	@awk '/__data_load_end/{printf("ROM used: %d bytes\n", strtonum($$1)); }' $(MAP)
+	@gawk '/__data_load_end/{printf("ROM used: %d bytes\n", strtonum($$1)); }' $(MAP)
 
 snek-duemilanove-install: snek-duemilanove-install.in
 	$(SNEK_SED) $^ > $@

ports/itsybitsy3v/Makefile

@@ -38,7 +38,7 @@ all: $(ELF) $(HEX)
 
 $(PROG): Makefile $(SNEK_OBJ)
 	$(CC) $(CFLAGS) -o $@ $(SNEK_OBJ) $(LDFLAGS)
-	@awk '/__data_load_end/{printf("ROM used: %d bytes\n", strtonum($$1)); }' $(MAP)
+	@gawk '/__data_load_end/{printf("ROM used: %d bytes\n", strtonum($$1)); }' $(MAP)
 
 $(SNEK_OBJ): $(SNEK_INC)
 

ports/itsybitsy5v/Makefile

@@ -38,7 +38,7 @@ all: $(ELF) $(HEX) snek-itsybitsy-install
 
 $(PROG): Makefile $(SNEK_OBJ)
 	$(CC) $(CFLAGS) -o $@ $(SNEK_OBJ) $(LDFLAGS)
-	@awk '/__data_load_end/{printf("ROM used: %d bytes\n", strtonum($$1)); }' $(MAP)
+	@gawk '/__data_load_end/{printf("ROM used: %d bytes\n", strtonum($$1)); }' $(MAP)
 
 snek-itsybitsy-install: snek-itsybitsy-install.in
 	$(SNEK_SED) $^ > $@

ports/mega/Makefile

@@ -63,7 +63,7 @@ $(HEX): $(ELF)
 
 $(ELF): $(SNEK_OBJ)
 	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
-	@awk '/__data_load_end/{printf("ROM used: %d bytes\n", strtonum($$1)); }' $(MAP)
+	@gawk '/__data_load_end/{printf("ROM used: %d bytes\n", strtonum($$1)); }' $(MAP)
 
 snek-mega-install: snek-mega-install.in
 	$(SNEK_SED) $^ > $@

ports/uduino/Makefile

@@ -38,7 +38,7 @@ all: $(ELF) $(HEX) snek-uduino-install
 
 $(PROG): Makefile $(SNEK_OBJ)
 	$(CC) $(CFLAGS) -o $@ $(SNEK_OBJ) $(LDFLAGS)
-	@awk '/__data_load_end/{printf("ROM used: %d bytes\n", strtonum($$1)); }' $(MAP)
+	@gawk '/__data_load_end/{printf("ROM used: %d bytes\n", strtonum($$1)); }' $(MAP)
 
 snek-uduino-install: snek-uduino-install.in
 	$(SNEK_SED) $^ > $@