Support for GCC14

[raiden00pl]

Many NuttX configurations doesn't compile correctly with gcc14 and some return new warnings.
Since correcting everything will take some time, I'm opening a new issue to track progress.

Here are the porting instructions: https://gcc.gnu.org/gcc-14/porting_to.html

TODOs

• new warnings for nimble - example: nrf52832-dk/sdc_nimble
  fixed here porting/npl/nuttx/include/nimble/nimble_npl_os_log.h: fix gcc14 error mynewt-nimble#1795
• libcxx compilation is broken - example: stm32f4discovery/testlibcxx
• include/crypto/curve25519.h:42:5: error: implicit declaration of function 'arc4random_buf'
• include/nuttx/net/netfilter/ip_tables.h:281:24: error: returning 'char *' from a function with incompatible return type 'struct xt_entry_target *'
• drivers/clk/clk.h:xx:5: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
• drivers/video/v4l2_cap.c:798:3: error: pointer/integer type mismatch in conditional expression [-Wint-conversion]
• [ ]

[augustofg]

The SPI generic bitbang implementation also fails with GCC 14 due to a function pointer incompatibility:

/home/augusto/repos/lnls/rffe-uc-fw/nuttx/include/nuttx/spi/spi_bitbang.c:257:22: error: assignment to 'bitexchange_t' {aka 'unsigned char (*)(unsigned char,  unsigned int)'} from incompatible pointer type 'uint16_t (*)(uint16_t,  uint32_t)' {aka 'short unsigned int (*)(short unsigned int,  unsigned int)'} [-Wincompatible-pointer-types]
  257 |       priv->exchange = spi_bitexchange0;
      |                      ^
/home/augusto/repos/lnls/rffe-uc-fw/nuttx/include/nuttx/spi/spi_bitbang.c:266:22: error: assignment to 'bitexchange_t' {aka 'unsigned char (*)(unsigned char,  unsigned int)'} from incompatible pointer type 'uint16_t (*)(uint16_t,  uint32_t)' {aka 'short unsigned int (*)(short unsigned int,  unsigned int)'} [-Wincompatible-pointer-types]
  266 |       priv->exchange = spi_bitexchange1;
      |                      ^
/home/augusto/repos/lnls/rffe-uc-fw/nuttx/include/nuttx/spi/spi_bitbang.c:275:22: error: assignment to 'bitexchange_t' {aka 'unsigned char (*)(unsigned char,  unsigned int)'} from incompatible pointer type 'uint16_t (*)(uint16_t,  uint32_t)' {aka 'short unsigned int (*)(short unsigned int,  unsigned int)'} [-Wincompatible-pointer-types]
  275 |       priv->exchange = spi_bitexchange2;
      |                      ^
/home/augusto/repos/lnls/rffe-uc-fw/nuttx/include/nuttx/spi/spi_bitbang.c:284:22: error: assignment to 'bitexchange_t' {aka 'unsigned char (*)(unsigned char,  unsigned int)'} from incompatible pointer type 'uint16_t (*)(uint16_t,  uint32_t)' {aka 'short unsigned int (*)(short unsigned int,  unsigned int)'} [-Wincompatible-pointer-types]
  284 |       priv->exchange = spi_bitexchange3;

The bitexchange_t type is defined here (returns an uint8_t and the dataout argument is also uint8_t):

nuttx/include/nuttx/spi/spi_bitbang.h

Lines 78 to 80 in ae0ef94

	/* This is the type of the function that can exchange one bit */
	typedef CODE uint8_t (*bitexchange_t)(uint8_t dataout, uint32_t holdtime);

But the spi_bitexchange functions have a different signature:

nuttx/include/nuttx/spi/spi_bitbang.c

Lines 67 to 78 in ae0ef94

	#ifndef SPI_BITBANG_DISABLEMODE0
	static uint16_t spi_bitexchange0(uint16_t dataout, uint32_t holdtime);
	#endif
	#ifndef SPI_BITBANG_DISABLEMODE1
	static uint16_t spi_bitexchange1(uint16_t dataout, uint32_t holdtime);
	#endif
	#ifndef SPI_BITBANG_DISABLEMODE2
	static uint16_t spi_bitexchange2(uint16_t dataout, uint32_t holdtime);
	#endif
	#ifndef SPI_BITBANG_DISABLEMODE3
	static uint16_t spi_bitexchange3(uint16_t dataout, uint32_t holdtime);
	#endif