Fix checking of negative with unsigned variables.
Check digestSz for 0 in wc_SSH_KDF() so that no possibility of dividing
by zero.
Change XMEMCPY to XMEMSET in renesas_sce_util.c.
Fix test.c to free prvTmp and pubTmp on read error.
Remove unused variables.
XFREE checks for NULL so don't check before call.
Move variable declarations to reduce scope.
* Add introspection for math build.
* Raise build error if more than one multi-precision math library used.
* Fix ESP32 to support using any multi-precision math option.
* Refactor math headers to use `wolfmath.h`
* Refactor of the opaque math variable type `MATH_INT_T` used by crypto hardware (QuickAssist, SE050, ESP32 and STM32).
* Cleanups for building with `WOLFCRYPT_ONLY` and `NO_BIG_INT`.
* Stop forcing use of fast math by default for platforms in settings.h. Note: For users that still want to use fast math (tfm.c) they will need to add USE_FAST_MATH to their build settings.
Applies To:
```
WOLFSSL_ESPWROOM32
WOLFSSL_ESPWROOM32SE
MICROCHIP_PIC32
WOLFSSL_PICOTCP_DEMO
WOLFSSL_UTASKER
WOLFSSL_NRF5x
FREERTOS_TCP
WOLFSSL_TIRTOS
EBSNET
FREESCALE_COMMON
FREESCALE_KSDK_BM
WOLFSSL_DEOS
MICRIUM
WOLFSSL_SGX
```
Added PRIVATE_D version of rsa private key operation for SP
implementation for specific platforms.
WC_NO_RNG results in warnings when RNG calls don't do anything.
Added ifdef checks for variables not used otherwise.
Remove superfluous if statements like when checking ret == 0.
Change names of globals that are generic and are used locally before
global definition.
Remove definition of variable len that isn't used except as a
replacement for sz which is parameter.
Don't subtract two variables when one has just been assigned the value
of the other.
Fix shifting of signed value.
Fix parameter checking in aes.c and des3.c for platform specific code.